6 to midnight?
At $10.00, I might do it occasionally, if there were a game or two that was something pretty special.
Of course, here's where it looks to me like you've kind of backed yourself into a corner:
1) You're asking on a collector site. A lot, if not most of the users here have games at home, and that's going to affect how much someone is willing to fork out to play games somewhere else, where presumably they'd need to put on pants.
2) For those who's interest is high enough that an arcade night sounds like fun, but not high enough that they own their own games, more than $10.00 just to get in might seem a bit steep, even with the unlimited play. It's hard for me to imagine someone taking a birthday party there, for example. A hundred bucks to get five people in who haven't eaten seems a bit steep.
3) Then you have the serious players. The people that used to piss off arcade owners by playing 6 hours on a single credit. They're not going to show up, which might be a good thing, or maybe not. Having someone just destroy a machine and put up a ridiculous score on a leader board might be a draw. If your arcade is known as the place where so-and-so plays, people might go just to check it out.
You're sounding pretty of serious. I would actually suggest reaching out to some of the successful arcades around the country, and see what they have to say. The local big-time arcade where I live does free-play nights every so often, and it's five bucks to get in. They seem to be well-attended. Maybe it's a loss-leader, and maybe they're making all their money on the beer and snacks. I dunno.
I don't mean to sound negative, I think you're on the right track with unlimited play: No coin mechs, no emptying coin boxes, no change machines. That greatly simplifies everything operationally, and completely removes a number of show-stopping points of failure. The answer's out there, I just think the question might be more complex than it seems on the face of it.
Good luck!