The main parks in Orlando are the various areas of Disney World, including the Magic Kingdom, The Animal Kingdom, and Epcot, which take a few days to take in.
Universal Studio's Island of Adventure Park is home to some large roller coasters themed around movie characters, as well as putting on stunt shows throughout the day.
Sea World is a great place to go to see dolphins and Killer Whales performing, as well as large Aquaria.
Ripley's believe It or Not harks back to the Golden age of Freak shows and is a fun day out for all the family, and a good change of pace from riding the roller coasters in the parks.
There are plenty of smaller parks to enjoy as well; including the God themed Holyland, amongst many small low rent others.