There are a few things we love to do at Ft. Wilderness, even if we are not camping there (which we also love to do) --
You can rent golf carts by the hour. You can't make a reservation for it, but you can call the Bike Barn from your hotel room or cell phone before you head over there to see if they have any available just for an hour or two. We did that in January and it was even sprinkling a little bit, but we had fun riding around, splashing in puddles, etc.
You can also go to their nightly Disney movie. They have a campfire (you can bring you're own stuff for s'mores or buy them at the chuckwagon), a sing-a-long, character greeting by Chip and Dale, and then they show a Disney movie right outside in their open theatre area. It's alot of fun. We rarely ever stayed for the whole movie, choosing instead to eat s'mores, watch the first bit of the movie and then move down to the waterfront for....
The electric water parade and fireworks. Lots of fun, and my kids even enjoyed being able to play in the sand and build sandcastles while the parade and fireworks were going on.
Have fun!!!