Marry: Jonas Quinn. This one was easy. He's smart and cute and seems to have a sense of humor. Plus, he's from another planet, so he's got that going for him.
Shag: Jayne Cobb. I know, he's crude and mean and generally a crappy human being, but he's just so dang hot. And big. I don't usually go for big, but there's something about those t-shirts that just really does it for me. Plus he'd go away right after and I wouldn't have to worry about him wanting to hang out.
Throw off a cliff: John Sheppard. Sorry, dude, but the whole martyr complex thing does nothing for me. Add to that the fact that I couldn't get through Calculus without a tutor and still got a C, and you have a recipe for disaster. Sure, he's smoking hot in an "I don't really care but they're paying me so I'll pretend to" kind of way, but that only gets us to the first time one of us gets sick and then the whole thing falls apart.