Seems like these sites are quite popular. However, I went during the middle of the week, on a slightly rainy day, at the end of August and was the only person there. 

If you're like me and not from Washington, remember to get a discovery pass (~$10 per day) if you're parking at the Baker Lake Trailhead. The hike in to Maple Grove is approx. three and a half miles. Don't be surprised if you run into some folks on horseback. 

The trail is relatively flat and goes through some beautiful old growth forest. We got a spot right by the lake that was flat and soft. All of the sites had fire pits and seemed pretty dispersed. There were also bear boxes.  The vault toilets were some of the cleanest I'd seen. 

As you can see from some of the photos, there's a dock that you could boat up to that doubles as a great place see Mt. baker.