Not sure why you think they are performing on that day to show the audience who may win that night (as opposed to it being just their job?), but we'll forget that part... my biggest issue going to NYC on Tony weekend was the amount of people calling out. Basically, anyone major who sang on the broadcast called out of my shows the Saturday before, since they probably wanted to be in good voice for the broadcast? So, I would worry more about how many slips of paper you may get, rather than the stage door. Since the stage door is easy to figure out, since you just stand there and they either sign, or not. They either run by, or not. So, it sorts itself out...