By writing "he loves music and the sciences," you've given an exact description of MOSI (Museam of Science and Industry). Not that far (in Tampa), the 45 min. drive is really worth it for him. MOSI has hands on interactive displays about music and science. They also include the IMAX dome theater and a lot of varieties of things to do, such as a room where you can experience a hurricane, ride a bicycle on a piece of string 3 stories high (yes, they made it safe), take control of landing a space shuttle in a real cabin, and others such as touching lightening or looking at a car with hail.
In NASA go to the Astronaut hall of fame, also have interactive science stuff like jumping on the moon, or experience different types of gravity.
If it's too cold for seaworld, you can visit the Flight museam, where you can see and ride in old planes out of Orlando.
In Plant City, the biggest strawberry town in North America, they hold their annual famous Strawberry festival in a fun rural area, a lot of fun!
Other Popular destinations worth to take a drive to:
Clearwater Beach in West Central Florida. Has #1 beach in America!
Busch Gardens
Aquatica (a part of Seaworld, much newer and I heard it was the best!)
Clermont- only as a detour, beautiful to drive through (towering hills and farms)
Tampa Performing Arts Center