Depends on the region and sometimes the local tradition. Each is a little different, but you an pretty much count on a presentation about what West Point is like, and how to make the most of your application. All that is usually followed by Q & A. Some will include a Cadet presenter, or ROTC as well, sometimes there are personal interviews, some are CFA events as well. All depends, but they are important to go to as that is your chance to meet and make an impression on the Field Force and Admissions Officers.