Good question. There are a lot of potential ultimate guy flicks. I've always been partial to The Terminator series (with part 2 being my personal favorite). There's sci-fi, guns, death, major action scenes, bad accents, sunglasses, leather, and motorcycles. It doesn't get any more "guy" than that. Similarly, movies like Rambo and Die Hard also come to mind.
The problem with all of those movies is that they're old as hell. More recent guy flicks would be Fight Club, a cult classic that every guy whose ever seen it loves. The Matrix trilogy (though I think part 2 sucked more balls than the on-call chicks from Bang Bros), is also heavy on the man side.
You know what movies never get old to guys? The mafia movies like The Godfather (parts I and II...you can live without III) and Scarface will always be winners. Also, Scarface and Goodfellas are winners.
If you go with any of the aforementioned "guy" flicks, you should be just fine. You'd just better hope he hasn't been waiting to watch Sweet Home Alabama with you!!!
As a chick who worked for years in an indie video store, I uses to hate it when guys came in looking for "chick flicks" for their girlfriends, and assumed I would know what a strange woman whom I'd never met would like better than her own boyfriend would. I usually just suggested my own favourites (I'm a chick, so since we're all the same, she'll like whatever I like), and sent him home with RoboCop, Dr. Strangelove, Pee Wee's Big Adventure, and Batman.
Not all guys like the same movies, and aren't necessarily into dick flicks. Focus less on "guy" movies, and more on movies you think he would like, or, if you don't know his taste, genuinely good films (for any gender). If you're looking at many many hours worth of movie watching and want to narrow down your options, try trilogies or series- the entire Star Wars or Star Trek collection. Also, focus on his mood and situation- if he's rehabilitating, maybe go toward inspiring stories like the Shawshank Redemption or the Mission. But he probably just wants a good laugh after an ordeal like that, so grab him some classic (or newer, as long as they're not from those "Scary Movie" jackasses) comedies, or, better yet, entire seasons of Futurama and Arrested Development- if he doesn't like that show, he isn't worth dating.