At Pitt, the fraternities had/have houses but most of the sororities were given a floor in Amos Hall that we could decorate as we dedided fit and, as long as the floor was at 100% occupancy, residence life didn't care who lived there. We didn't have to do the lottery like the other dorms - thank goodness.
Two houses, KKG and KAO, did have houses off campus complete with house mom and all. But I wouldn't have liked that, especially walking those extra blocks to class. Plus, the quad our dorm was is was kind of the middle of everything.
ETA: Here's a picture I found of sisters in the formal end living room. So you see it doesn't look very dorm-like at all
