We were fortunate to have a friend who is a local give us some great tips on places to eat. Here are my reviews....
NEAR AULANI:
Just Tacos - across the street from Aulani, decent Mexican food at touristy prices; we were put off by the loud music inside, would request to be seated outside
Zippy's - these are all over the place and the nearest one is in Kapolei (by Safeway); I kind of think of as the Hawaiian equivalent of Denny's, they serve the classic plate lunches at decent prices
Hapa Grill - haven't seen this place mentioned on this thread yet, it's also in Kapolei near Safeway; they serve great breakfast and dinner here at reasonable prices
http://hapagrill.net/
Costco - if you're a member, you really can't go wrong with a dirt cheap Costco meal

also lots of souveniers and Hawaiian foods available here
Roy's - didn't get a chance to eat here as they had a fire during our visit
Paradise Cove - it's a decent luau, and apparently the one the locals prefer; I though it was a bit touristy and the food just OK; drink lines get horrendous, get in line early!!
WAIKIKI:
Rainbow Drive-In - probably my favorite meal of the trip; the best plate lunch on the island!
Leonard's Bakery - you absolutely must go for a hot malasada! there is also a Leonard's truck you'll see parked at a shopping mall near Aulani on the north side of H1 (I think near the Home Depot)
International Market - a bit touristy but lots of fantastic cheap meals at the food court; you can get a Dole Whip here!
Cheesecake Factory - didn't eat here but hadn't seen in mentioned yet on this thread but there is one near Waikiki Beach; always a safe bet
NORTH SHORE:
Giovanni's Shrimp Truck - this is where we stopped due to the reviews and it was pretty good; apparently the shrimp comes from Asia; don't miss the BBQ corn from the stand behind it!
Ted's Bakery - stop here on your drive along North Shore; they are famous for the chocolate haupia pie...get one to take back to Aulani with you!
Aoki Shave Ice - Matsumoto's next door is more popular but this is where the locals go! very friendly and delicious shave ice! get vanilla ice cream and beans with it!