I went to a fair event hosted by The MBA Tour.
I think that everyone has something to learn when attending these fairs, no matter how far along the admissions process someone is. I have some friends who just became interested in pursuing an MBA so they went to the fair – they found it extremely helpful since there's tons of information on schools readily available for students. Plus, there were some seminars that explained the application process, and because they were just beginning the process they learned a lot of new information.
However, for students who have already done plenty of research on schools or the application process (students like myself), I don't get the same benefits from that kind of information. Instead, I went to a fair with the intention of getting face time with representatives and speak with them to learn more of the intimate details of their program. It's actually quiet revealing of a program how alumni or representatives present themselves and speak about their program. I don't think a new student would be able to pick up on these subtleties, but after thoroughly researching some schools I was able to learn even more about certain programs through this.
Plus, just by going to these events and meeting with representatives can help you in the long run by putting a face to your application. While students are still able to do this at individual school info sessions, these types of fairs allow new students to gain a ton of information and allows 'veteran' students to learn more detailed information about a lot of schools at once.
The MBA Tour fair I went to was free (as I think they all are) so there's really no commitment. I just filled out an online registration and that was it. Hope my response helps anyone else that stumbles across this thread