Clare Newsome:
I think period dramas/timeless movies (eg sci-fi like Star Wars where there's v.little visible 'tech') age best, as there's no comtemporary styling to date. For example, I love Blade Runner, but the parts with computers/screens haven't aged well.
Hence The Godfather (already mentioned) can work cos of its period nature. I could (and usually do) watch that on an annual basis and still leave with a sense of awe.
I'd add Raiders of the Lost Ark and Moulin Rouge to the list from my own personal favourites. And the Big Lebowski.
There were a lot of very good "proper" films made in the 70s that stand the test of time because they are properly acted, have real stories and do not get shielded by special effects. A lot of films today will be forgotten as the computer imagery will look dated in a decade. Dialogue is different. Pulp Fiction will be raved over in years to come because of that fact alone.
And Clare, I agree about the period/timeless point but you always find a turkey. The 70s gave us The Godfather and then there was Road To Perdition!!!!!!!! Now that was a stinker.