My DS is 11 now but some of his favourites that i have noticed being mentioned are:
Sky High
All 3 Spy kids movies
Catch That Kid
The Last Mimzy
Flight of the Navigator
Space Camp
The Sting
Big
Shark Boy and Lava Girl
Bill and Ted's Excellent Adventures (there a couple of sex jokes in this but they still go right over DS's head)
Adventures in Babysitting
Splash
The Back to the Future trilogy (there is the scene where Marty plans to take advantage of his "mom" in the car and the Biff comes and tries to really do that so it may be more than you want to get in to)
Ghostbusters
Short Cirtcuit
Yes it is R and I have no idea why. I can possibly see P-13 (which was available when it was rated) but not R at all I let DS buy it for DD for Christmas the year he turned 8 and she turned 10