I've visited the campus, and I wouldn't call it gorgeous (lots of buildings that were clearly built in the '60s and '70s), but the central part of campus, where most of the academic buildings are located, has nice tree-lined walkways, benches everywhere, and places for students to stop and grab some food. I'm guessing it's really nice there when the weather's warm.
The current grad students I spoke with told me that living off-campus is definitely a better option. Stony Brook has a very good off-campus housing website: http://och.fsa.sunysb.edu/. Hope that helps!