I'd like a building that could be used as a hang-out place that everyone could sit around in and chat, goof off whatever. Maybe some vending machines and a pachinko machine would be nice. Perhaps the friendly atmosphere would provide a healing / energizing effect.
There could be one or two large community centers and perhaps a smaller local neighborhood center for each neighborhood that would require a key of some sort.
We could leave notes there, leave unwanted items for others to use and...