Between its cheerful catalogs and its sought-after spa services, Bliss has sewn up a devoted customer base. Nibble on a brownie while awaiting your oxygen facial, detoxifying herbal hot wrap, or jet-lag-busting massage. Subway: F, V to Broadway-Lafayette St.; N, R to Prince St. Other location: Bliss, 19 E. 57th St., between 5th and Madison Aves., 3rd fl., Midtown East, PHONE: 212/219-8970; Subway: N, R, W to 5th Ave./59th St.