Perks of Being a Wallflower. Unusual choice maybe, but there is a very distinct quality in the movie. It's like a book in movie form, probably because the writer did most of the writing for it too.
And yes, Life of Pi, man it's artsy. Add Cloud Atlas to the list as well. It's more about the ideas than the action and scenery. Oh, Pan's Labyrinth. Sticks with you and you just appreciate the sort of dark quality it has.