After picking apart many of my childhood films, I too have been thinking on what films may be useful for my son, and others' children instead of the parade of morally perverted drivel that comes out of many a film studio's doors...
I find it best to steer away from most disney films, but only because they perpetuate sexual stereotpyes, inequality, gender-abuse etc, etc... I am also mindful of films that have a covert boy-meets-girl things tagged on the end, as well as strongly expressed moral dialogues smothered with cuteness, humour and princessification. And most sequels are even more full of manipulative and propagandised bullsh*t than the original. There are no doubt many other ways to determine what may be good for my child at his/her stage of life... your child/ren will no doubt be very different at all the stages in their life and a film that may hold a great moral quality at one age could go right over their heads if shown to them in other stages.
I find that (As long as I know enough of the issue explored in the film myself) discussing a film with my son afterwards is very important. So many parents just pop a DVD on and leave their kids to it. Actively watching films with your children and discussing it to a degree is a very responsible thing to do. It teaches them that firstly, their opinion is important and valued, and it also helps them cultivate their own critical thought processes so they too can understand 'why the Queen is doing that' or 'why the King is going to war' etc etc...
Stef has covered many films and the idea of fantasty. Fantasy is something that I am still exploring, so I'm not certain on this yet, but it may be useful to show children films that are relevant to their lives at whatever stage they find themselves. Erasing certain types of fantasy (or atleast shelving them for now) could be a useful differentiation.
Films that I think can be very valuable to children; easy to understand (without hollywood or product placement, gender programming etc) include:
Ernest & Celestine (Great one for tolerance and freindship)
The Secret of Kells (Creativity, authority, perseverance)
Terry Pratchetts Hogfather & Going Postal
There are many, many more, I will add more as I remember them!