Yeah, I do think the dorms do make a huge difference. You don't have choice of room mates so you might get stuck with a weirdo or drug addict or someone who isn't too shy about what is done with their girlfriend in your room :x . (sorry, had friends stay at my apartment because this happened.)Plus you can't get away from things in dorms, there is nowhere to hide.
I would think most Christian schools are somewhat better. At least there wouldn't be blatent sin being flaunted. Or I would hope not.