We had a wonderful camping trip at Lake Rabun. The campground was fairly empty when we went (a weekend in late August). There are two separate camping areas. We stayed in the one across from the entrance to the beach and boat area. I think the other loop is more geared towards RV camping. Some of its sites have electricity and water, but none on our loop seemed to have that.
Our site (32) is known as Charley's Hole for the small waterfall that is just behind the site. It is said to be haunted by Charley, a man who had a stroke on the campsite. It was his favorite site to stay at, and his kids posted a sign on the campsite in his honor. We didn't see any sign of any of the ghosts the camp host warned us about, but we definitely enjoyed the peaceful sound of the creek twisting around the campsite.
Lake Rabun is a beautiful lake tucked away in the mountains. There are lots of opportunities for fishing from the shore, dock, or a boat. There is a no wake zone around the beach and boat ramp, but there are quite a few fast moving boats in other areas. It's a beautiful place to explore by kayak, but I suspect it would be hard to keep balance on a paddleboard outside the no wake zone.
Our trip to Lake Rabun was extremely peaceful. There is no cell coverage there, so you are truly left to enjoy nature at its finest. It's secluded enough that you should plan on bringing everything you need -- the nearest stores are a fairly long and windy drive away, no matter which way you go.