Walt Disney World
It's hard to ignore the magic of Disney World! It may take all day just to figure out which park to explore! Check the website for information on park admission, places to eat, special events, and more!
Universal Studios - Orlando
Rides, thrills and movie magic galore! Now with The Wizarding World of Harry Potter at their Islands of Adventure park, I admit I am hoping to find myself wandering over that way for a day! Again, above link will bring you directly to park info. Staying at Disney? Not a problem - here are some transportation ideas (that don't involve brooms or Floo Powder, sadly).
Kennedy Space Center
If you're a space nerd like we are, or want to make the trip a more educational experience (y'know, for the kids...really...), Cape Canaveral and the Kennedy Space Center is about an hour from Orlando. As with Universal, there are a few transportation options if you don't want to rent a car. Although the Shuttles are no longer in use, a little birdie has told us that there is currently a rocket launch scheduled for 13 January (the Monday after the wedding). Launches are notoriously unpredictable, though, so check frequently for updates as the date gets closer.