It depends on what you are into:
sports: golf, fishing, RPDE, marathon, bowling, ESPN Club, WWS/ESPN Zone, etc
shopping: DTD, area outlet malls, large scale malls
drinking: Jellyrolls, Raglan Road, monorail tour of resorts, walking tour of resorts in the Boardwalk area
movies: DTD 24 screen theater some with meals served by waiters
night clubbing: Jellyrolls, Atlantic Dance, Raglan Road, Citywalk
resort tours: monorail tour of resorts, Boardwalk around the lake tour of resorts, AKL/AKV
offsite: Gaylord Palms Resort, Citywalk, swamp tour
Outside of WDW, at Gaylord Palms Resort; they have 3 acres under a glass roof. The area under the roof is divided into three areas Key West, Everglades, and St. Augustine/type fort. There are fish, snakes, gators, etc that you can view. You can spend 3 to 4 hours over there touring the resort/areas and it does not cost anything.
You can be as busy as you want or as relaxed as you would like too.