This is a hike by I-90 near Seattle, in Ollalie State Park. You need a parking permit. https://www.wta.org/go-hiking/hikes/mount-washington-1
Instead of coming down the way to went up, we hiked to Change Peak and down to a different trailhead, that's a short walk from Mt Washington TH. See the attached map.
The trail to Mt. Washington is very crowded, rocks on trail, well marked and maintained. The trail to Change Peak sees few people (we met 6 in total, and no one between Mt. Washington and Hall Point - half way down from Change Peak). It's overgrown, a bit muddy.
Mt. Washington is 20-30m higher, better view. The top slope is very nice and meadow-y.
There's a bit bridge over Change Peak, which looks quite impressive. The creek is nice to wash off sweat or dip your feet in.