I'm thinking about turning the walls into a giant coloring book, maybe of a jungle scene. I envision getting an art projector and penciling in grasses and trees and animals. Or, now that I think about it, a coral reef scene would be better.
From there, I'd either get acrylic paints or bright markers or something and invite people to color it in, so it would be a collaborative art project. Actually, the more I think about it, the more I like the reef idea.