At my university we have sorority suites, which are located in the dorm. There are 5 NPC sororities on campus and 5 floors in the dorm, so each sorority has a specific floor for their members with a suite at the end of the hallway. The door to the suite has a touchpad number lock on it, in which only the sorority members know the numbers to get in. Members are offered first priority of living on their sorority floor, and then if it is not filled it is offered to any university student wanting to live in the dorm. I know that for my sorority, the rooms are always filled with Alpha Gams, so there is not anyone outside of our sorority that lives on our floor.
The university really has no imposed regulations of what we do. We have 24 hour access to the suite, and many of the girls that live in the dorm go in there to cook (we have a kitchen), study, or do chapter related activities. As far as having "sleep overs," I guess we could all stay in the suite if we wanted to (there are no rules against it), but there is honestly not enough room for 100+ girls to spend the night in there! Also, when it comes to mixers, parties, or events there is again not enough rooms for all our girls and other people to fit.
As far as I know, we have always had sorority suites, whereas the fraternities have houses. Our university is currently looking into building sorority apartments around a new sorority complex, but I'm sure that will be another 10-15 years before it ever happens
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