I think the crowds at WDW will be light considering most schools are still in session. I would definitely take a trip to US/IOA. If your boys are adventurous, then I'd suggest IOA, which has a lot of great rides, but most are thrill rides. US has the ET Ride, Barney Show, Woody Woodpecker's Fun Zone(with a kid's rollercoaster, play area, wonderful water park, etc.), Jaws, Kongfrontation, Twister, etc. Personally I prefer IOA but that's because I'm a thrill ride freak.