My 48 year old husband LOVED it. Your 6 YO will, too!
There is a great book called the Unofficial Guide to Disneyworld. It's like $17 but is worth every penny. It really helps you to plan wisely.
Start with Animal Kingdom - lots of boy stuff there - safari, Expedition Everest, Dinosaur and the shows are great Nemo and the Lion King.
Hollywood Studios is amazing too. He'll love the stunt shows and the Toy Story ride.
There is so much to do at the Magic Kingdom that he will love! See Mickey's Philharmagic (saw it twice), Pirates of the Caribbean, Peter Pan's Flight, the Haunted Mansion, the Roller coasters - I can go on and on and on! He will love it. Makes me sad that I am not there right now!! :(