One suggestion for those building for children.
Young (6 and under) kids LOVE cocktails. They can play them while standing up. And once they get older they can play them sitting.
A good compromise machine usuable by both dad and the kids (without taking up a buttload of space) would be a single sided cocktail (which could go up against the wall or in a row of uprights). The kids can play it standing, and dad/mom can play it using a chair.
I built one like that once. It is a pretty quick and easy build. To imagine it, think of a standard classic upright, then chop it off at the control panel (with the monitor facing straight up), and then lower it down until the panel is at cocktail level. Note, I am not saying to modify an upright that way, I am just saying that is what it looks like.