We left Seattle at 5am and got to the trailhead by maybe 7:30am. The road up to the trailhead is long, dusty, and washboard-y, but we saw vehicles of all types—even motorcycles—make the trip. When we arrived there a few vehicles near the Tolmie Peak trail sign, and maybe 20 cars down by the campground. When we left at ~12:00pm the entire lot was full and cars lined the road for some distance.
The trail was in good condition, albeit bumpy/rocky/root-cover in some places. This was our first hike using trekking poles and I'd highly recommend it, they really help you to keep your balance and take load of your legs. Eunice Lake was pristine, we made it there in just over an hour. The hike up to the peak is only maybe a mile(?) but very steep. Views from the top were ridiculous…ly gorgeous! There was a massive lenticular cloud positioned above Rainier but didn't block the view. There were maybe 10–15 people at the top, but most dispersed and by the time we head down there were only 4-5 nearby. 10/10, would hike again.
Other notes:
• When we got back from the hike bathrooms by the campground had a massive line. We gave up and just used the bathrooms 10mins up the road by the paybox for the park.
• If you 100% can't make the full hike to the peak from Eunice lake I recommend going up the first third to the slope where you can near equally good views of Rainier and Eunice lake.
• If you do have a high-clearance vehicle I recommend trying out the little obstacle mounds near the Evans Creek ORV area. My Jeep is no Wrangler, but it was fund to climb up the rocky mound.