Did this as a two night, 3 day backpacking trip with a day hike to Tatoosh Buttes over 4th of July weekend. We started at Billy Goat TH and followed Hidden Lakes trail (via the passes), described by others here. This trail was absolutely beautiful but there are some cons to consider. The primary issue we had was a surprising lack of camping spots near any of the lakes aside from a few tight spots on Cougar Lake. However, near the trail cabins between Firsts and Middle Hidden Lakes (also referred to as the guard stations--they are locked and not for public use), there is one public open walled shelter on the First Hidden Lake side. There are also a few somewhat "hidden" spots if you follow the path near the toilet sign and keep the stock tie-up to your left. Cross a few fallen logs and you'll find a great little spot, which was thankfully pointed out to us by the fishermen hanging out at the shelter (thanks guys!!). I have read online, and this was confirmed by the fishermen, to avoid camping close to the cabins due to rodents. None of the spots have great lake access except the shelter, so don't have high hopes of taking a dip. Second, the trail gets harder to follow once you get past the cabins, essentially turning into a stream bed before mellowing out again. We hoped to get to Big Hidden Lake our first night, but we were exhausted by the hike in, so we turned back and camped at the aforementioned spot. On Day 2, we hiked to Big Hidden Lake then doubled back to near our camp to hike Tattoosh Buttes. This was a tough but really fantastic addition to our trip that I'd highly recommend if you have time. The trail junction is unmarked, but surprisingly not hard to find currently. It's between First and Middle HiddenL  in an area with thick brush and a fast flowing (loud but not visible from the trail) creek to the west. You can actually see the trail going up the ridge which should be an additional cue if you're not following a map (would highly recommend gpx though). The immediate start to the trail is very steep and sketchy but the trail quality improves and is very easy to follow all the way to the Buttes. The trail passes through burn, forest, through alpine meadows, and finally to the top of the ridge with amazing 360 views of the surrounding landscape. We saw no one on this trail and it felt very magical and otherworldly. There were a few snowfields at the top but nothing treacherous. There's no signage at the top and the trail continues on toward the other peaks. We had a snack and turned back the way we came, finally arriving at our camp in the early evening. On both days we saw loons on the lake, but didn't hear them; we did fall asleep lullabied by the sweet, low, buzzy "peent!" of common nighthawks. Our third day we hiked back the way we came. The trip back for whatever reason felt much more challenging but overall it was a fantastic long weekend!!

A few random notes:
The trail can be very exposed during some portions, so bring sunscreen. Plenty of water on the trail right now. We drove to Winthrop on Thursday night and stayed at the River Pines Inn before hitting the trail early Friday AM. It was a little pricey but suprisingly cute, comfortable, and homey, with a great spot for drinks overlooking the river. If driving from Seattle to Winthrop via Rte 20 (via the Cascades scenic byway), the road is GORGEOUS, just keep in mind there are very few places to stop and eat/get gas/supplies. If you do need to stop, we had a solid American-Korean fusion dinner at Mondo's in Marblemount (there's also a local gas station with an amazing variety of stuff) but slim pickings overall. In Winthrop things close early, keep that in mind if you plan to hike out late Sunday. There are public showers at the RV park in Winthrop as well as a laundromat in Twisp, just bring cash or quarters. There's also nothing between Winthrop and the trailhead in terms of supplies/gas stations/etc. So definitely stock up and be ready to go before leaving Seattle. The road to the trailhead was gravel but otherwise extremely easy to drive. Additionally there are a number of first come first serve campgrounds along the road that would be excellent for pre-hike zzz's if you don't want to fork over money for a stay in Winthrop. Busyness wise, it wasn't completely desolate (we saw about 5 couples/groups on day 1, two of the same couples on day 2, and 2 couples on day 3) but definitely high on the solitude meter for a holiday weekend. The exception was Tattoosh Buttes, where we saw no one at all.

Birds to listen/look for:
Western tanager, western wood peewee, hermit thrush, common nighthawk, Townsend's solitaire, white-crowned sparrow, mountain and western bluebird, Clark's nutcracker (Tattoosh), Canada jays, Wilson's warbler, loon

Hiked from Slate Pass to Tatoosh Buttes, then climbed Ptarmigan Peak and continued past Dot Lake, around Mt. Lago to Butte Pass, down and back up to Shellrock Pass, then past Doris and Fred Lakes on my way back to the Middle Fork of the Pasayten and up to Slate Pass.  This was some beautiful hiking, but the portion from Dot Lake to Butte Pass was strenuous.

The drive up to Slate Pass is rough at times, but I imagine all vehicles can make it - you just may need to drive slower than the average bear over the potholes/washboard if you are in a small car.  From the trailhead, the hike down the Middle Fork of the Pasyaten is slow, steady, easy, and in good shape.  On my way out, I saw a pack train carrying in supplies for a WTA work party.  I imagine they were going to do work out by the abandoned airstrip; the trail is in good shape all the way out there, at least by my eye.

Headed east towards Tatoosh Buttes, and the trail begins to climb through an old burn.  The views become magnificent as you ascend, but one caveat - once you cross Lease Creek, there was no water until a small spring that was developed that crosses the trail on Tatoosh Butte (see photo).  The hike across Tamarack Ridge was beautiful, and the ascent of Ptarmigan Peak was fun.  From the peak, I dropped off towards Dot Peak, then went down the steep scree/boulder slopes to Dot Lake, which was lovely and had many small trout rising to its surface.  I then traversed from the lake towards a spur ridge that came off Mt. Lago, and hiked down the very steep walls of that ridge into upper Ptarmigan Creek Basin, where I traversed at about 6400' and then climbed up to Butte Pass, where I rejoined a trail.  

The trail leading from Butte Pass to the valley floor was still very intact, and although it is overgrown once you reach the valley floor, well-placed and very visible cairns marked the route up to Shellrock Pass.  From Shellrock, it was a bit of a slog down towards Eureka Creek and up to the pass above Fred and Doris Lake; the trail had its fair share of windfall; but it was not difficult to navigate (except for a short stretch where I lost it just after it crosses the creek after descending from Shellrock Pass).  Then a quick hike down to the Pasayten River, and back to the trailhead.

The off trail section was a challenge, and I relied heavily upon my Green Trails Map.  Overall, this hike was exceedingly beautiful, and the environment felt very remote, which was a lot of fun.

  Brief account of a 4-night backpack to Big Hidden Lake with side trip to Tatoosh Buttes.  One small patch of snow on Eightmile Creek Road very close to the end, but it was gone by the end of our trip.

  Trail 477 is pretty much completely clear as far as the intersection with Tatoosh Buttes trail. The trail is heavily eroded, and very dusty (or possibly muddy) thanks to the pack animal use.  It could really use some trail work (water bars etc.); or fewer heavy animals tearing it up.  The trail also goes through recently burned forest beyond First Hidden Lake, so logs will be falling in the future.

  The trail between Middle and Big Hidden Lakes is pretty wet and has become a streambed in some places.  Beyond Tatoosh Buttes trail there are a lot of burned logs down across the trail.  Nothing impassable, but certainly slows you down.  Middle and Big Hidden Lakes seem a bit murky - possibly from sedimentation or fertilization post-fire? 

  We hiked past Tatoosh Buttes trail perhaps a half-mile to a campsite on Big HIdden Lake, with lots of down trees around.  Saw some otters and loons on the lake, as well as hearing nighthawks and owls.  Also had bad mosquitoes one night (but not the other), and black flies.

  Went for a day hike up Tatoosh Buttes trail to the Buttes.  Lots of flowers all the way up.  Maybe 30-40 trees down across the trail.  Most are just a step-over, some require a little off-trail scrambling.  Several streams flowing.  Some very small snow patches were on the trail just before cresting out on the buttes, and some snow patches in heavily drifted areas up there.  Trail in decent shape except for down trees.

  Not a whole lot of camping along the Hidden Lakes, but one campsite at east end Cougar Lake, 2 cabins and a shelter between First and Middle, and the small campsite on Big Hidden that I stayed at.

Left a cloudy Slate Pass around 10:30 Wednesday morning and hiked across Buckskin ridge. Soaking wet brush made me wish I'd packed gaiters. The trail across Buckskin was easy to follow and mileage accurate to Silver Lake. The lake was decent enough. Continuing past the lake the trail was considerably rougher and not always where USGS or Greentrails indicated. At one point, beyond Silver Pass, it drops far into the valley, goes down a bit,then climbs straight back up. Some blow down and difficult places to follow approaching Buckskin Lake but overall not bad. The signed and mapped mileage claimed 10 miles, I recorded 12.5. Buckskin Lake was a decent place to stay and I had it all to myself. One tragedy: I'd forgotten my spoon! Second time this year. I did remember that episode of McGuyver where he goes camping and forgets his spoon so I was able to cup up my beer can for a make-shift option. Overnight all the clouds blew away leaving a great star show. Recorded 12.5 miles with 3200ft gain. Some good trail, mostly rough trail. In the morning I debated a quick trip up to Buckskin Point but opted to just hike out since I was unsure if the mileage had any more surprises. Happily it was smooth sailing down to the river trail. At the Tatoosh Butte trail junction I found a sign indicating a washout ahead, the first I'd heard of. I went back down the trail aways to a marked cabin site to see if I could find anyone with more information but instead just found a flattened old cabin. Thankfully the washout was easily bypassed on foot. On the other side the trail was still easy to follow until Lease Creek where it entered an old burn. Most of the blowdown had been cleared but it was quite brushy until I climbed up above the burn, then easy going. Fanastic walking through high meadows along the ridge where I left the trail and went to the top of Tatoosh Buttes. Great place! I stayed up here a bit then took a lower route across Tamarack Ridge looking for water. I found a pretty smalll but clear stream and refilled before moving on to Ptarmigan. Easy walking to the top of a faint path but the length of the day was catching up with me now. Views from Ptarmigan were great in all directions! Well worth the two days to get here. I looked for a register but didn't find one. I had planned to drop down to Dot Lakes for the night but instead opted to make camp near the little tarn on the ridge. It let me have a high camp, still get Dot Peak and visit the lakes, and have a better view of the Perseids. Only downside would be a very cold night though I could live with that. I lounged around a few hours until sunset, watched a great colorful show, and turned in early. I set a 1 am alarm and woke to great stars and another night with faintly visible green from the northern lights. Perseids were going strong, the best show I'd ever seen. Recorded 16 miles with 4950ft gain. Mix of good trail, bad trail, and off-trail. In the morning I packed up and made a quick visit to Dot Mountain. Nice little peak! I had considered going through the col between Lago and Carru but I couldn't see a snow-free path. Going across in the early morning without snow travel gear was definitely a no-go. So instead I descended to Dot Lakes. Really beautiful lakes! So many larch. I saw a tent here, the first sign of a person since I started my trip, but no sign of its occupant. I refilled my water and began the long traverse out towards Butte Pass. I knew not to drop down to the Ptarmigan Creek trail. Every report of this one without fail mentioned it as an overgrown and unlogged misery slog. By comparison staying along the hillside wasn't bad. Some talus hopping, some meadow travel between sparse larch, and so on. Crossing the shoulder of Lago through a steep but treed gully wasn't terribly fun but worked. On the far side I opted to go higher onto the ridge rather than keep going out to Butte Pass. This worked though it did go through some steep dirt and rock ledges that were not pleasant. In hindsight just continuing the traverse out to Butte Pass would have been easier. Over Butte Pass I dropped down on trail and found a very nice tarn in the basin! Far too shallow to swim but very pretty. I had lunch here, soaked my feet, and eventually moved on to Shellrock pass. Emphasis on "rock". The trail faded in and out in the meadows but the higher parts were all fist-sized rocks. Views from the pass were nice though. Now it was once again down into another valley on rough trail. Easy to follow but rough, a bit overgrown, and some blowdown to make things interesting. Eventually I climbed back up towards Doris Lake on improving trail. I reached the lake a bit before 5pm, claimed a nice campsite, and called it a day. The lake was very pretty and just warm enough for a swim! The rest of the evening I just lounged around with my book. I saw one hiker go past into the higher campsites but no sign of the other occupants of the bigger tent. Overnight the clouds again blew away for one last great star show. It was also again colder than forecast and I really wished I'd taken the weight penalty to bring my 10 degree sleeping bag. Recorded 10.2 miles and 3800ft gain. About half off-trail, the rest crummy trail. Up reasonably early I decided to skip Osceola for a return trip and began the long hike back to Slate Pass. Somewhat rough and steep down to pretty Fred Lake and down to the main river trail. Then easy, fast, smooth sailing all the way back. Be warned many of the junctions are poorly signed and one major junction simply goes down to a massive horse-camp on the river. I crossed paths with several large groups heading into the cabin at the Pasayten airfield. I think it was a WTA volunteer vacation. They said nobody camps in the cabin due to mice but stay nearby and use its facilities. On my hike in I had no views from Slate Pass, now I had great blue skies! There was also a Forest Service pickup at the trailhead and a sign with information on the washout. Also cars parked in every single wide spot of the road. Popular place! I made the slow drive down the road and thankfully didn't meet another car coming across Deadhorse Point. Bought a great sandwich at the Mazama Store and a beer, drove up the highway to eat these at the Diablo Overlook, then the long drive back home. 12.2 miles with 2450 gain on the way out, almost all on very good trail for speedy travel. What a great area! I'll definitely be back.