I had a great experience with my cabin stay at the Dam Site Recreation Area. The cabins (built by the CCC in 1940) are true to their original design and construction, but appear to have been well maintained with all plumbing, air conditioning, etc. working nicely. I stayed here on one night of a long family road trip and it was a refreshing change of pace from the usual hotels. It was nice to leave the windows open at night for fresh air and wake up with a great view of the marina.
One note: If you are arriving late, as I was, make arrangements in advance and be sure to ask for directions (it's dark in the state park). (I didn't call until after office hours, arrived very late, and I ended up being pretty confused and waking the management up at 11:30 at night. Credit is due to them for being remarkably friendly and helpful despite the circumstance!)