Hi ya, Kasaundra! Your son is a lucky duck. The first park we always hit is Magic Kingdom. I'm a sucker for the nostalgia of Main Street and seeing the castle. I hope they both feel the same about me.
If your son craves adventure and excitement at 11 year old (although a Jedi craves not these things), he'd have plenty of thrill attractions to experience at Magic Kingdom, such as Space Mountain and Big Thunder Mountain. His interest might be piqued even more by what Hollywood Studios (Rock 'n' Roller Coaster, Tower of Terror, Star Tours, etc.) or Epcot (Test Track, Soarin', Mission:Space, etc.) have to offer.
I'd recommend you let him make the choice if you don't have a preference. A fun way to start creating your attraction "hit list" is by visiting the
Disney World Customized Maps page. You can learn more about attractions and add them to your own customized maps, which Disney will professionally print and mail to you free of charge.
Regarding park tickets, I'm a big fan of the hopper option. If you're on the fence, here's what I'd recommend: if you'll be in town for 4 days or less, get the hopper so you can visit your favorite park more than once.