Roy's Restaurant   Finally, we don't have to drive east or west anymore to have Roy Yamaguchi's signature blackened ahi (it never gets tired, does it?). His Hawaii Regional Cuisine can only grow in popularity now that there's one in Waikiki, with Kauai-bred Jason Peel at the helm. Like Alan Wong, Yamaguchi (who's constantly busy at events such as the Gourmet Institute in New York or an Adriatic cruise) lets his proteges get creative. While every Roy's has the signature entrees of macadamia-crusted fish, that ahi, misoyaki butterfish and hibachi-grilled salmon on the menu, the rest is up to whoever is in charge of the kitchen. At the new Beach Walk location, Peel's winners have included his version of surf and turf: red wine-braised pork osso buco with shrimp carbonara risotto. And what we like about the original Roy's, besides Ronald Nasuti's food, is the fact that we get an internationally known, high-end restaurant and a neighborhood hangout wrapped up in one.  Honolulu: Waikiki Beach Walk, 226 Lewers St. 923-7697. 5:30-10 p.m. daily. Hawaii Kai: 6600 Kalanianaole Highway 396-7697. 5:30-9:30 p.m. Mondays-Thursdays; 5:30-10 p.m. Fridays; 5-10 p.m. Saturdays; 5-9:30 p.m. Sundays. Ko Olina: 92-1220 Aliinui Drive. 676-7697. 11 a.m.-9:30 p.m. daily. Reservations recommended. AX, DC, DS, JCB, MC, VS. Checks accepted. $$$.  Web site: www.roysrestaurant.com