Wow, you make this game difficult! :) I'll start with the easiest and work my way backwards:

Chuck: Christopher Eccleston. No offense to him, he's cute in his own way, but he is in third place to my other two choices.

Marry: Eddie Izzard. He's not really my type but he is SO FUNNY. And not funny in a way that would annoy me after a while, but funny in an intellectual, irreverent, but never mean funny. He seems like a sweetheart.

Shag: James Roday. If I knew more about him, maybe I would want to marry him instead. ;) But he is definitely shag-worthy. So cute!