I'm in a similar situation. I have had the chance to visit 2 campuses of the 14 I applied to, and I honestly don't see a way for me to visit the others because of cost and time.
I can definitely get a feel for students from the message boards, talking to alum, etc...but my main concern is housing. I'd like to see some places and take a look at possible areas before deciding on an apt without really getting a chance to check out the location.
I'll probably end up waiting until I get admissions decisions back from my top choices, then out of those do a general search on the areas, the school, etc. and base my decision on that. Once I narrow it down to 2 schools, I'll try to visit them if I can.