We stayed at Minneiska campground since Cedar Hills is under construction this year. It's a newer campground so the vegetation hasn't grown in fully yet - your neighbors are visible but there's good distance between sites so it wasn't a problem at all. The grounds themselves are really well-kept with nice bathroom facilities and hot showers, which was perfect for the cooler fall days. It's a busy park so you'll need to reserve early or plan on visiting during the week.
The hiking itself was awesome. We did the Dakota trail, which was a tough up and down hike with really incredible views of the fall colors. There's also a nice park/picnic area with beach access. I'm hoping to come back next summer to enjoy the swimming. All in all it was a great stay!