Field of Dreams. Watched it a couple weeks ago, and my wife kept trying to talk to me near the end. Brutal.
But honestly, for the first time in my life, I was completely enthralled for the entire 100 whatever minutes of it. I hadn't watched it in about 10 years or so, and I think the mental processes in my brain that have developed in the meantime really helped me 'get' it.
Moneyball was absolutely great too. I know Keith Law didn't like it or whatever -- "Keith Law disapproves" of just about everything -- but it was a baseball movie that didn't bastardize the game, and didn't pull too many punches.
I mean I like the 'fun' ones; Angels in the Outfield is great if you aren't looking for a ton of realism, but I hate the movies that make baseball seem as easy as it looks on TV. It just feeds the stereotypes that non-baseball fans have....i.e. it's boring, etc.