Though this place is years past its peak as a music-industry after-hours hang, China Club still has the Jade Terrace, a top-floor indoor-outdoor garden. The meaty door guy and the metal detector downstairs may make patrons think they’ve reached some inner sanctum of New York nightlife. They haven’t. And they haven’t seen their last doorman, either; the terrace has yet another. Each of the three levels has a bar, and on the weekend, each seems to represent a different geographic wedge of New York’s suburbs.