Mai Tai Bar   Who says a bar in the middle of a shopping mall can't have appeal? Not you. As a matter of fact, if given a choice, you're happy to drink here, and only here. The al fresco, patio-like space, the cheap happy hour, the live music and the friendly crowd help with the mass appeal, but let's face it: The folks at Mai Tai pour one heck of a cocktail, and when it comes to good bars, that count for a lot.  Ala Moana Center, Ho'okipa Terrace, 1450 Ala Moana. 947-2900. 11 a.m. - 1 a.m. daily. Happy hour: 4-7 p.m. and 8-11 p.m. daily. AX, DC, DS, JCB, MC, VS. No checks. $.  Web site: www.maitaibar.com