I am new to this board, so here it goes: I recently spent a week in hawaii (maui and kauai), and am posting my results from a couple of restaruants visited. Please note that after hotel and tour provided meals on Kauai (except Roy's), i tried to get local fare suggestions from the concierge at Maui. That proved useless, so as a tip, ask tour guides about local restaurants. They can be gold mines.
Da Kitchen (Kihei, Maui) - This place made fantastic plate lunches. I opted for chicken ktasu, and beef teryaki. Not only do you get heaping, monstorous portions, but the price is reasonable, and the meat was tender and tasty. (Didnt have much room for the pasta salad)
Mamas Fish House (Paia(?), Maui) - An expensive, local fish house. The fish is caught daily (the menu tells you the name of the person who caught each type of fish), and if it is not used, it is sold to market. We had opakapaka (pink snapper) that was incredible, mahimahi/pork combo, also delicious. We also had an ahi poke lumpia appitizer, which was amazing. Money is well spent here, and its not going to Nicks Fish Market. Kinda touristy, but its set in a nice, peaceful area.
Some steakhouse in Makawao, Maui - Makawao is a small town, so I think there is only one steakhouse. On monday nights after 530pm, all you can eat prime rib for $19.99. The prime rib was juicy and tender, and the service was top notch. However, they only make a certain amount, so if they are out, you are SOL. There was also a mexican joint just down the street that we wanted to try.
Roys (Kauai) - Cant miss restaurant here, although they are scattered all over hawaii. You definetly have to visit it at least once. Butterfish and Snapper were excellent, the chocolate souffle even better.
Bubba Burger (Kihei, Maui) - Good burger joint with Jorhnny Rocket-ish hamburgers. I had a double burger (nice and juicy) with nice crispy onion rings. However, the vegetarian burger was a little dry. BTW, they have pins that have a McDonalds logo with a big cross in front of it. Very funny.
KKO (Kihei, Maui) - Another touristy restaruant, but the price was right. You can get a fresh catch of the day for $13, and its prepared really well.
The Fish Co. (Lahania(?), Maui) - Mediocre food for a mediocre restaurant in a very touristy part of town (There were $7 dollar pay lots, fer christ sakes). We had luau quality ribs, and a decent pasta dish with scallops and lobster. After dinner, we walked around and found a little plate dinner joint we wished we saw beforehand, since we would have eaten there in a heartbeat. Cant recall the name, though.