First off, late May is
NOT a good time to go to theme parks in Lake Buena Vista or Orlando. Go during the Fall season when the temps are cooler and less people/crowds.
That said, if you're looking at this trip for entertainment, skip Walt Disney World. On the other hand, the food at WDW is :thumbsup::thumbsup:.
In order of which WDW theme parks are fun (for those older than 10-years-old ):
Animal Kingdom > Epcot (especially for food!) > Hollywood Studios > Magic Kingdom
I suggest skipping WDW and go to Islands of Adventure in Orlando. Everyone (all ages who can get in) should go on the Harry Potter and the Forbidden Journey ride.....it's badass. The new area, The Wizarding World of Harry Potter Diagon Alley, was still being built when we went (a couple of years ago), but everything I've read about it seems like it would be fun. Order Butter Beer (non-alcoholic drink) while you're there too. Mmmm. Islands of Adventure rockkks.
Next day, go to Kennedy Space Center over by the coast. They're not offering the specific tour we went on (Mega Tour which was 3.5+ hours long where we went inside the Vehicle Assembly Building and got to stand 100 yards from Launch Pad 39A), but the "Explore Tour" and "Launch Control Center Tour" look somewhat comparable.
Go on an Everglades Tour to see alligators. We did it by Tram,
http://www.sharkvalleytramtours.com/, but there are other places you can go by airboat.