Rum Fire   At this hotel restaurant/lounge/bar, instead of kitsch, there's class: dark wood interiors accented by brilliant shades of amber and setting-sun orange. Instead of walls, the beachfront restaurant is brilliantly equipped with floor-to-ceiling windows that open up to an incredible view of the ocean and Diamond Head. It's about time a Waikiki hotel thinks about us too, and the good folks at the Sheraton Waikiki designed Rum Fire for everyone, not just tourists. There's a long cocktail menu designed by a world-class mixologist, not to mention the state's only rum bar complete with 100 different kinds of rum from 20 countries. And the sophisticated menu, with its local ingredients and tributes to Island-style grinds, is entertaining and appealing.  Sheraton Waikiki hotel, 2255 Kalakaua Ave. 922-4422. 4 p.m. midnight Sundays-Thursdays, 4 p.m.-2 a.m. Fridays-Saturdays. Valet and validated self-parking. AX, DC, DS, JCB, MC, VS. No checks. $$$.