I've never been to one either, but I've seen the ones they do at ROH shows. Generally, if its a big star, the line is outrageous and you should at least have something to be signed or be prepaired to buy a 8X10. The indy guys will usually hold a brief convo with fans or pose for a picture and shake you hand. It all depends on the talent. I would suspect Flair would require some type of purchase, and I doubt you'll get any sort of substantial conversation out of him.
I've seen Nigel McGuinness and Bryan Danielson spend a lot of time with people. At the Edison shows, the only bathroom is in the front lobby, so its not uncommon to have Necro Butcher in front of you on line, and Austin Aries taking a leak in the urinal next to you. Not the best time to mark out.