Re: Great Aikido/MA Kid films
What about the old Karate Kid movies? Not much in terms of actual techniques, but if you're throwing in "Kung-Fu Kangaroos" just for the message, I think even though the movies are a bit "corny" the message within them is still good. Right there you have 4 movies, that kids can watch, understand and maybe relate to that don't contain any special effects enhanced martial arts.
Depending on the age of the kids, A. Kurosawa films might be a bit much, still the dueling spear scene in the "Hidden Fortress" is worth seeing, beautifully choreographed.
"Aiki" is good, more of an adult version of the Karate Kid movies, and does have actual Aiki related moves in it. They even mention O'Sensei in a discussion.
The new King Kong movie features a scene with Kong fighting several dinosaurs, and that choreography was very reminiscent of Aikido...if you can get through the first hour of the film without falling asleep...