I've gone to 2 national conventions. Both times, it seems that people hang out w/ those from their region. However, since over the years, I had developed online relationships with sisters from California, we (the Florida contingent) were hanging out with them. In fact, on our "free" day last convention, a group of about 18 alumnae from both states wandered around Epcot together.
But on another note, I have a Cuban friend who joined Phi Mu at Florida International Univ. She told me that when she went to convention, it was so obvious that her little group stuck out, esp. their style of dress. (Miamians tend to dress a bit flashier than other parts of the country..