There is plenty for boys at Disney!
My DS was 6 the first time we went... he had a blast! He stood in line to meet the characters, loved the shooting galery in Frontier Land, the Fort & caves on Tom Sawyer Island, Splash Mountain, Thundermountain Railroad, Space Mountian and Buzz Lightyear's Space Ranger Spin... I could go on and on.
Now he's 10, still loves the same stuff! I asked him recently if he thought he'd like to go again... "Are you kidding! I LOVE that place!"
The amazing thing to me is that at home he is all "I'm cool, I gotta impress everyone with how grown-up I am" but when we get to Disney he relaxes and is just a kid again! He will even wait in line to hug a character... I keep thinking he'll outgrow it, but he hasn't yet!
As for Princesses since we have no girls... I don't get to enjoy them as much as I'd like but I have to admit some of my favorite memories are of when "mr cool" was thrown a kiss, hugged or winked at by a princess... it's the only time I ever see him blush!