We've been staying at the Salt Springs Recreation Area in Ocala National Forest in north-central Florida. The actual springs (pictured) allow swimming in crystal clear water that is a constant 72F year-round.
The grounds and buildings are immaculately kept with neat trails and walkways. The camping facilities are among the best we've ever seen and the staff is friendly and helpful. Campsites are all large and feature full hookups (50A, H20, Sewer). Just $34/night - even less if you have a Federal Parks lifetime senior pass. Suggestion: check the campground map and try to book in a site located in the north half of the campground; you will experience less road noise.
We also made a side trip to Cedar Key, about 2 hours west on the Gulf. It's an old tin-shed-Key-West-type fishing village with an interesting history as a lumber and rail terminus as well as pencil manufacturing -- of all things.
Check out the haunted Island Hotel (and restaurant/bar) on 2nd Street, and don't miss the shops and eateries on Dock Street. For food: try Steamers for lunch or dinner and Annie's Cafe for any meal (including breakfast).
Monday we tour St. Augustine, which is located about an hour northeast of Salt Springs.