It's no secret that sometimes a girl just needs a little time away from the boys. The crop of popular female-only clubs around the country takes the concept of ladies' night to whole new levels. Now London is jumping on the bandwagon, opening up its first girls-only luxury health club this week. With a boutique service that handles all Net-a-Porter.com purchases, Grace Belgravia is definitely the chicest health club we've ever heard of. For those of you in need of girl time, but who can't quite jet off to London, click through for some New York-based girls-only clubs to try.