Slate asked several directors and critics to name the movies they've rewatched the most. Spike Lee names "Election." He's watched it more than 40 times. Excellent choice. I've rewatched that one a few times. Nowhere near 40 though. [CORRECTION: Slate's layout confused me. Spike Lee names "West Side Story," with zero commentary, and the next guy, Adam McKay, a director I'd never heard of, names "Election."]
Lots of other interesting choices -- along with some crushingly boring ones. I mean, even if your true answer is "Citizen Kane," please spare me. I wrote that before reading through the whole list and getting to Dana Stevens, who begins: "Leaving out the movies everyone's seen countless times (The Wizard of Oz, Citizen Kane, It's a Wonderful Life)...." I suspect most of the answers followed that rule without saying it.
I love this subject of what you want to rewatch. To watch something the first time is to respond to some mysterious mix of your own imagination and the various things you've heard. Maybe something about a poster or some feeling about a movie star pulls you in. Then you find out if it was what you thought it would be or if you're surprised in a good way. But rewatching a movie, you know basically what's there, and you're making a choice to relive what you know or you have a sense that there are places in there where new things can be found. It's a richer, deeper experience. Oh, that reminds me of what Andre says about marriage -- as opposed to an affair -- at the end of my most rewatched movie, "My Dinner With Andre."
ADDED: Neo NeoCon responds.