Hi, Shelly! If you have a sports fan, you may want to check into the ESPN Wide World of Sports. You can check out the events calendar to see what may be taking place during your visit in April. April seems to be chock full of exciting sports events, with spring training in baseball, golf, lacrosse, and track and field. You can check out the full schedule by going here
ESPN Wide World of Sports.
I've done the late teens with my now 20 year old daughter, and she has always loved Walt Disney World. If he's a thrill seeker, check out Rock 'n' Roller Coaster and Tower of Terror at Disney's Hollywood Studios, and the "mountains" at the Magic Kingdom (Space Mountain and Splash Mountain). There are some great shows at EPCOT - like comedy and Celtic rock in the UK. Don't forget to brave the Yeti on Expedition Everest or ride back in time on Dinosaur!
Let him do some of the planning - choosing some of the dining experiences or planning one of the days during the vacation. That can help generate some interest on his part.
I hope you guys have an awesome vacation!