Yes, your kids like those giant plastic Habitrails that loom over every fast-food burger joint. But wouldn't the little rowdies like a real playground even better? One that's outdoors? One with sand, shovels and buckets? One where they can keep their shoes on? Joe's Crab Shack has thought of all that. And it serves food on the patio next to the playground, so while you eat, you can watch your kids zoom down the slide and wobble across the little swinging bridge. They're reasonably happy; you're reasonably happy. And these days, when public spaces are designed either for kids or grown-ups but rarely for both, that mutual happiness seems an accomplishment.