Oahu & Maui
You are right K-Man, search the threads. It's like when I want to visit Chicago, I don't just ask what is good/hole in the wall/etc. I am more specific. It gets kind of wearying posting the same things over and over again on generic requests. Hunt gave a good list though of the usual suspects. A new one to try on the windward side is Heeia Pier General Store, a new little deli reopened at the famous Choy site (not Sam) recently. They serve plate lunches and a killer ahi sandwich that is $7.50 which seems high to some but if you realize they are serving fresh fish brought right to them from the boats that come into the harbor it's amazing.
Their offerings are somewhat few but they just opened so take that into consideration. You cannot go wrong on the location and waterfront (true waterfront) setting.
Hey! A new one to me.
PS - trying to steal my young wife away (O`ahu only this time) in September, so might have time to actually try some new spots, but not miss any "old favs." Wish that the North Shore fine-dining had not slipped so badly, as we'll probably do 6 days (with golf) over there at one end of the trip.
For Maui, you might want to see this thread: http://chowhound.chow.com/topics/783216
For O`ahu, my recs. for fine-dining are:
3660 on the Rise
Hau Tree Lanai
Great food, but lower-end:
Nico's Pier 39
PS - I have posted reviews of most of those, over the last 5 years. Just do a Search, and adjust the time frame.
Alan Wong's Restaurant
1857 S King St Fl 3, Honolulu, HI 96826
Chef Mavro restaurant
1969 South King Street, Honolulu, HI 96826
2199 Kalia Rd, Honolulu, HI 96815
Hau Tree Lanai Restaurant
2863 Kalakaua Ave, Honolulu, HI 96815