The boy and I went to Vegas for his birthday. Not to gamble, not to drink. To go to the Pinball Hall of Fame. We spent the whole weekend there. It was pretty fun, I have to admit. They have row after row of *playable* pinball machines.
Surprisingly, I really enjoyed playing the older machines where it's more about chance and less about skill. The games where you get see the electric jolts and hear the little metal bells. I also really liked playing "Pinball Circus," a prototype machine that never got made and of which there are only two in existence. That particular machine did cost $1.00 per game, but you get 5 balls and I scored a few replays. The newer machines are either $0.50-$0.75 per game, and the older machines are just $0.25 per game.
We brought my 9-year-old niece along for a few hours and she really liked playing on the "ping pong" machines too.
My only suggestion would be a snack bar with chairs. I mean, when you're playing pinball for several hours straight, it would be nice to sit and relax for a few minutes with a sody pop.