I did the extended loop plus an extension out-and-back to Coal Creek Falls (adding 1.5 miles), for a total of 9 miles and 1800' elevation gain. Even without Coal Creek Falls, the extended loop adds 400' down and 500' up as you descend to Shy Bear Marsh and then go over Long View Peak. Although a few muddy spots, it's easy to step to the side of them. The many boardwalks at the marsh and Whittaker/E4 trail were scenic and fun. All the intersections are well signed. Take the King County map (linked below) with you (or take a picture of map at trailhead).
I recommend the counterclockwise direction as described by WTA. The Whittaker/E4 trail below Shy Bear Pass is steep and rough compared to the better shape Gombu/E5 trail. Someone with clippers could clear some shrubs and branches near the E4 trail. Doughty Falls is smaller than Coal Creek Falls but easily worth the short side path. Trees block the view from the Long View Peak bench. Shy Bear Marsh is mostly unseen, except where the trail crosses it on the west end.
The parking lot had only 3 cars at 8:20 am on Friday. By 1 pm it had 10 with a few spaces still open. There's one porta potty.
Bugs were absent much of the hike although a few times a non-touch nuisance. A couple flies landed on skin near the peak and along the Shy Bear Marsh. No stings, just annoying.
Flowers are plentiful. White and purple trillium, bleeding heart, false Solomon's seal. Even the salal and Oregon grape sported flowers. At the marsh were skunk cabbage beginning to bloom (and smell for better or worse).
Beware the stinging nettles along the first half mile of trail. At the top are huge devil's club but those are obviously no-touch.
Lots of pretty moss and ferns on trees and big boulders (licorice fern) plus sword and bracken throughout the forest floor. The vine maples have half-opened leaves. Soon the forest will feel more "full" with the leaves.
Lots of bird sounds. Saw a pileated woodpecker (red head) flying near the marsh, and heard one at a distance. Junkos hopped along the trail in front of me partway up the peak. Other than that only slugs and a caterpillar and occassionally a human or two (some with quiet dogs).
No berries yet but in a month you'll have Salmonberries galore followed by red huckleberries.

Comments