Not only does DKNY embrace the lifestyle store concept, but it's a lifestyle with a relatively short attention span. New merchandise arrives frequently, so there's always something new to wish for. Cocktail-party ensembles, chunky-knit sweaters, and knockaround denim vie for notice; the "pure" line is reserved for all-natural fibers. A scattering of vintage pieces, such as leather bomber jackets or 1930s jet jewelry, ensures that you can have something no one else has. Scout out the nonwearables too; the candles, toiletries, and home accessories are unfailingly cool. Then you can belly up to the juice bar, log on to an in-store iMac, or listen to a featured CD. Subway: N, R, W, 4, 5, 6 to 59th St./Lexington Ave. Other location: 420 West Broadway, between Prince and Spring Sts., SoHo, PHONE: 646/613-1100; Subway: C, E to Spring St.