I need to start a thread for "recommended movies to watch with your son or daughter." Maybe I already did and I forgot about it.
I have a daughter who is 8 and a son who is 11. We just watched Bill and Ted's Excellent Adventure, and the three of us all loved the sh$t out of it. Wholy enjoyable time for everybody. Yes, somewhat dated. Yes, a bit cheesy, but a great message, some funny one liners, hot-chicks-but-in-a-tame-kind-of-way, some dramatic tension, and enough slapstick to keep the kids interested. For a dad and his kids, this gets highest mark. I can't believe the same movie that I enjoyed as a 16 year old they enjoy as 8 and 11 year olds. But whatever.
So this movie gets included in the "fun for dad and kids," along with this mix of classic and recent:
Iron Giant
Ghostbusters
Goonies
Searching for Bobby Fisher
August Rush
Airplane
Field of Dreams
The Sandlot
The A-Team
The Princess Bride
Back to the Future
Men in Black
Support Your Local Sheriff (my favorite when I was 11, and my son loved it)
Oh Brother How Art Thou (this was a stretch for my son, but he made it through)
Apple Dumpling Gang
Sound of Music
Chitty-Chitty Bang-Bang
These are all rentals that I've watched with them in the last 3 years, are a lot of fun for your 8-12 year old (or your nephew or niece), and have a lot of "rewatchability" so you will have fun watching with them.
I think I'm going to try and take it to the next level and bring Raising Arizona to our family vacation. I think the first 20 minutes will make my son's head explode. He LOVES slapstick.