THe other posters have hit the mark with the thrill rides. Spiderman is a most unique ride and does have quite a thrill in it. Don't miss Toon Lagoon at IOA by thinking of it as a kiddie area. It isn't. There you will find two of the greatest water rides anywhere. Ripsaw Falls is a Flume ride with coaster elements with the best drop. Period. Bilge Rat Barges is an awesome river rapids ride. Nearby you will find Jurassic Park River Adventure, another water ride with an exhilarating drop. As everyone else said Dueling Dragons is a must and you must ride both Fire and Ice. I haven't ridden front row, but DH says it's worth the wait.
At USF, the Mummy is a must for coaster enthusiasts. If you get a seat in the last row, you will get lots of airtime.
I also wouldn't miss:
Shrek 4-D (funny 3-D movie with puts you right in the action with the added effects)
Terminator 2 (3-D show combined with live action)
The Horror Make-Up Show (Hilarious!...Don't miss this one!)
MIB (you are in training to be a MIB agent so you shoot the aliens and compare your score with others...can be addictive)
ET (neat ride with great theming you should go on at least once)
Jaws (it's a classic)
Catch the Blues Brothers street show too if you can.