Discovery Zone, man. I actually feel bad for the kids that never got to experience Discovery Zone. Lasted for like 2 years. It apparently failed because they had a mountain of debt (all those plastic tubes are capital intensive buildouts) and adults had to sit around while their kids played.

I feel like if you made it work like a gym membership for your kids, and had something for adults to do off to the side, you might be able to make the numbers work.