I was in Hawaii for Christmas 07.
The tonkatsu place next to the Embassy Suites is victory, and the Italian restaurant next to that is awesome too. And uh, drive to the north shore, cuz it's a cool drive and you get to see some crazy surfing (at least I did when I was there). Lock your car when you get there. There's also some famous Hawaiian food van on the North shore, which was pretty good, maybe not worth the epic wait.
That's about it from me. The last time I was in Hawaii I spent 2 days dicking around in Oahu (was awesome), one day on Maui (saw Tom Arnold, who was super hammered at noon at the Four Seasons, awesome), and the rest just reprehensibly drunk on a fucking cruise ship with intermittent stops around the other islands.