A couple quick notes from a recent trip:
Mama's Fish House: Ate lunch upon arrival. Wonderful,beachside setting. Superb fish - probably best food I've eaten in state of Hawaii. However, you pay. Fish entree was $35. My daughters "keiki" dish, which consisted of about 5 bites of Kalua (sp) pork, a cup of steamed rice and 3 bites of cole slaw was $15!!!! And dinner's more. Given it's location in the middle of nowhere, I'd eat there either upon arrival or departure, or if you're windsurfing of returning from Hana. Just too far to drive from the West/South.
Sansei in Kapalua: Good sushi. Some excellent "unique" dishes, like a deep fried tuna roll. Crab salad roll nice as well.
Pioneer Inn at Lahaina Harbor: Ate there while waiting for ferry. Nice location at harbor, friendly staff. Food is mediocre.
Maui Onion at Renaisance resort: Excellent location overlooking ocean, terrific burger and mahimahi sandwich. Oh, onion rings crispy and delicious.
Kihei Cafe: Good burger and smoothies. Cheap and easy.
Otherwise, Sheraton Maui had surprisingly good food. And of course the Safeway got repeat visits.