At the school where I initiated:
1 all female dorm, 8 wings, double rooms.
1 all male dorm, 8 wings, double rooms
4 coed by floor/wing dorms, 9 wings, double rooms
2 coed by floor/wing dorm, 8 wings, double rooms
1 coed dorm by floor/wing, 11 or 12 wings, all double rooms except one wing of singles
There was some sort of visitation policy that all guests had to be registered with the front desk, but it was NEVER followed. I stayed in my dorm to visit when I was underage and I may or may not have shacked a whole lot - particularily after I've moved out.
At the school where I'll graduate from:
I believe there's currently 10 dorms - some are converted housing because they took way too many freshmen. Some are living on my street in a former halfway house! The dorms range from quads with common bathrooms to singles with a private bathroom and
most of them are quite nice.
There's also upperclassmen/grad housing in the form of apartments - again, everything from studios to a 5 bedroom townhouse.
The visitation policy here is apparently pretty uptight, I never lived on so I'm not entirely sure. I do know, however, that my mom managed to have overnight male guests in the 70s, so I'm betting it's still easy to violate.