If you thought Michael Kors’s retail empire couldn’t get any bigger, take a stroll up Madison Avenue. The fashion designer’s latest endeavor is a 6,655-square-foot lifestyle store, his largest one yet (667 Madison Ave., nr. 61st St.; 212-980-1550). The two-story behemoth houses the affable Project Runway judge’s Hamptons-ready shoes, jewelry, and shades (from $89) as well as signature handbags (from $695) on the ground floor and ready-to-wear clothing in the basement. Shoppers can browse the goods in spaces accented with mirrors, Macassar wood, and Calacatta marble, while taking inspiration from Kors’s most recent runway shows, looping on an eighteen-foot, multiscreen video display.