In August we drove down to the Eagle Creek Campground, just east of the Swift Reservoir, and spent the weekend with the Scroggins. There were nearby public campgrounds, but they were booked by the time we decided to start looking. For future reference, a campground I've wanted to try for a long time down there is the Lower Lewis River Falls Campground, which as the name suggests is very close to the Lower Lewis River Falls.
On the first full day there we drove up the Lewis River, doing a couple of small hikes, and taking in the scenery. There were quite a few waterfalls we got close to, a few of them were pretty spectacular. The second day we drove up to windy Ridge Viewpoint on the east side of Helens, and took in the sites around there. On the way home we took a small detour to see the Iron Creek falls (which we've seen before on trips to the Iron Creek Campground).
On our way down at the beginning of the weekend we drove down I-5 until the appropriate exit, and then headed east on a windy and sometimes bumpy road to get to the campground. I was not impressed. On the way home we decided to take the route directly to Randle, and then head East towards White Pass, before turning North to Enumclaw. This route was rougher than the way down, but definitely a lot prettier.