For days, weeks even.
Halfway because of the score honestly, the theme stands as one of my favorite pieces of music EVER, and the rest is just so darn atmospheric.
Anybody who hasn't seen it and wants to give it a shot, watch it alone, at night, in the dark. I know that's basically the ideal way to watch most movies but I swear to you, you won't regret it.
Following close behind for completely different reasons is Pacific Rim. Something about giants fighting other giants that always gets me, always always always.