Freestanding indoor playgrounds with snacks
Many fast food restaurants have done pretty well with attached indoor playgrounds. However, some of us prefer not to feed our kids junk food every time we need some indoor playspace. There are plenty of structured or semi-structured gyms and such for children, but very few indoor playgrounds for simple, active freeplay.
So here's the idea: have a playground indoors. Have an all-you can eat snack bar that is filled with only simple, healthy foods. Charge admission.
The basic playground ideas can be found anywhere. Just put it inside so it can be used whatever the weather. Use sound absorbing design and materials so the happy voices of many children will not echo and make the space unbearably loud.
The snack bar should be simple, healthy items: carrot sticks, apple slices, cheese cubes, etc. Besides any desire for "healthy" food, this would allow people with food allergies to easily find something they can eat. And children will happily eat fruit and vegetables when they are not competing with french fries. Organic and/or local food would be even better. It would probably work out best if snacks are in individual kid-sized cups (perhaps 1/2 cup), rather than expecting harried parents and klutzy kids to deal with tongs and plates. Avoid extremely messy and/or allergenic items, like peanut butter.
There should be enough staffmembers on hand to keep the playground clean, the snackbar stocked, and maybe pass out bandaids if needed. Children are not admitted without a supervising adult. This is a playspace, not a drop-in childcare facility.
Have plenty of tables and benches for supervising adults to sit. This is a space where parents can relax, socialize, do paperwork, whatever, while keeping an eye on their children.
Don't forget the little stuff. Have a nice bathroom, with toilets and sinks of various sizes. Have a comfortable nursing area. A small padded romping area for infants and young toddlers might be nice.
If you wanted to get even more elaborate, a separate quiet room for older kids and teens to play boardgames or do homework without interference by pesky younger siblings.
Reward: Build one in Seattle, preferably in the downtown area! I'll happily pay admission. If this idea was supporting sustainable agriculture (local and/or organic), that would also be a lovely reward.