When the runway lights dim and the flashbulbs fade, the real fashion week magic happens behind velvet ropes and candlelit tables. From power lunches to late-night martinis, these are the A-list hangouts to hit up during New York Fashion Week.   Balthazar A cornerstone of SoHo chic since 1997, Balthazar is more than a French brasserie—it’s a fashion world fixture. The intimate, velvet-red dining room is lined with antique mirrors and warm globe lights. Because what’s Fashion Week without mirrors…