I just finished watching The Godfather: Part II, watched Apocalypse Now yesterday, and watched The Godfather about a week ago. Sure is a lot of Francis Ford Coppola. They were all extremely long, almost too long, but I loved each one of them. This was a round of first viewings for me, but I hope to re-watch them in the future.
I don't know if I could really decide a favorite between the three. Apocalypse Now was my favorite visually, the plot in The Godfather was the most exciting, and the structure of The Godfather: Part II was the best. The Godfather had the best looking woman.
I've been advised that The Godfather: Part III isn't really worth the watch, and a friend and I read through the plot on Wikipedia. I don't intend to watch it anytime soon. Michael is remorseful over something he did in the second movie, and I think that was enough to turn me away.
I know these movies are very well seen, so most of you have probably already seen them, but I would recommend them all. They're the opposite of what I would consider a light watch, though. So, be prepared of that.
Any other movies by Mr. Coppola that I should be sure to get to?