I think there should be a rule that movies can't be longer than two hours. I'm looking at you, Peter Jackson.
If a movie is exactly two hours, it's going to be at least twenty minutes longer than that with previews. Do you know how I feel after sitting in a movie theater for over two hours?
1) I have a headache
2) My butt hurts
3) I have to pee like whoa
The last is a major consideration. I was recently at a movie with my husband that was three hours long with previews and he went to pee twice during the movie. And his bladder is much bigger than mine, if anatomy class is to be believed. Think how us women feel!
And who makes all these really long movies? Men.
I really don't believe that there's any story that can't be told in two hours or less. It's called editing. No matter how awesome you think every scene in your movie is, we're going to miss a bunch of it anyway due to having to run out to pee.