I enjoy almost anything by Quentin Tarantino. My favorites would be Pulp Fiction, Kill Bill, and Reservoir Dogs.
I don't think any of those are that great for learning seduction, except for maybe Bruce Willis, John Travolta, and Samuel L. Jackson (his serious, Byronic side) in Pulp Fiction.
As far as seduction, I agree with PrettyDecent on Casino Royale, absolutely fantastic. Brad Pitt and George Clooney do an excellent job of being sexy, but not that many movies I like, except for Troy and O Brother, Where Art Thou?.
Ah, I almost forgot Looper. Joseph Gordon-Levitt can be one sexy man. James Franco can be pretty damn sexy too, but most of his movies don't portray that side (like 127 Hours).
Even though it's not a manly movie, Jude Law exhibits some brilliant fundamentals (facial, etc.) in the Holiday (recently watched it in December, so on my mind).