Lewers Lounge   We're in despair that Dale DeGroff is no longer Halekulani's director of beverage arts, but we can take solace in the king of cocktails' legacy a menu of drinks classic and contemporary made only with juices that were squeezed that day. Head bartenders Elaine Harrington and Timothy Rita Jr. shake and stir concoctions such as perfect martinis, lemon-and-honey Bees Knees and Brazilian caipirinhas sweet with muddled grapes. Porcini-dusted sliders and Brie en croute are on the fun yet sophisticated bar menu. And Tuesdays to Fridays Hawaii's Frank Sinatra, Bruce Hamada, croons and works his standup bass in the noirish, woody room.   Halekulani hotel, 2199 Kalia Road. 923-2311. 7:30 p.m.-1 a.m. daily. AX, DC, JCB, MS, VS. Checks accepted. $$.  Web site: www.halekulani.com