This is a good early season hike while its still rainy in Seattle it can easily be sunny and warm on the other side of the mountains. There are at least 5 good campsites at the lakes that will each hold multiple tents no problem. Some people do light fires but I’d like to discourage it, fire danger is pretty real in these scrublands. This is a very pretty hike full of sage brush and interesting geological features, also several waterfalls. Past the lakes you can go out to the Columbia River Gorge. Check out the WTA description for more details. Note that there is no potable water, you have to haul it it. The lakes are contaminated by irrigation run off.
This is one of my favorite areas to backpack in, the Alpine Lake Wilderness. My preferred camp site is right on Surprise Lake, though there are more if you continue on to Glacier Lake. I’ve camped here twice, one in the winter and another time last summer, both were very pleasant, but you should be warned that there aren’t any amenities, and you definitely need to bring a water filter. Also it can easily be much colder at the lake than Skykomish.
No promises, but I haven’t found it to be overly crowded, seems like more people do it as a day hike (only 11 miles round trip, but you could connect up with the PCT to increase milage). I’ll let the pictures do the real selling.