Niel,
I am sure you have thought about it, but Cape Canaveral would be top of my list, also it might be worth checking if there is a Shuttle launch while you are in Florida.
From
http://www.nasa.gov/missions/highlights/schedule.htmlDate: March 11 +
Mission: STS-123
Launch Vehicle: Space Shuttle Endeavour
Launch Site: Kennedy Space Center - Launch Pad 39A
Launch Time: 2:31 a.m. EDT
Description: Mission STS-123 on Space Shuttle Endeavour will deliver the pressurized section of the Kibo Japanese Experiment Logistics Module (ELM-PS) on the twenty-fifth mission to the International Space Station.
With recent history of the Space Shuttle, there's a good chance the launch will be delayed so could well occur the week following the race. KSS is an excellent place to spend a very long day - we didn't arrive until about 11am and didn't really have enough time to see all there was to see. I'd definitely return next time we're in the area.