The Snow Lake Hike is one of the most popular hikes to do in the Seattle area. My son and I went on Wednesday morning, and by the time we left the lake to head back down (2:30ish), there were tons of people coming to the lake. It’s about 7 miles round trip, rocky, but moderately easy with the elevation (good for kids 6ish and up). A great place to bring lunch and hang at the lake or keep going another couple miles to the smaller Gem Lake if you want to get away from the crowds (strongly suggested for weekends).
Not a bad way to spend a summer day!