supernatural, horror, & scifi

The geography of Xanth, the setting of 42 novels by Piers Anthony, is based on Florida. So while not strictly set in Florida, these books have a strong Florida connection.

From Wikipedia: 

"Geographically, modern Xanth resembles the state of Florida in the United States in shape, but has landmarks that mimic well known geographical features from around the world. One major example of this is the Gap Chasm, an enormous canyon a mile wide which completely bisects the country ... [like the] the Cross Florida Barge Canal, which, similar to the chasm, is generally forgotten except for those who stumble upon it. The Gap is guarded by a resident dragon, known as Stanley Steamer, and is crossed by means of treacherous bridges. Many of Xanth's other geographical features are puns on those of Florida (for example, Lake Ogre-Chobee and the Kiss-Mee River). The Florida Keys also exist, though they are, in Xanth, actual keys."