Cheap eats: Cilantro Mexican in Lahaina--a block or two off Front street, great inexpensive fresh Mexican. Also love Honolua Store in Kapalua (near the Ritz). They have an amazing deli where you can get great homemade food in generous portions for not a lot of money. We love to stop there and get some stuff for beach picnics, stash it in our cooler, then go exploring. For Sushi we love the Sushi place at the Ritz (Kai?) and Sensei--there are a couple on the Island. Sensei has a late night happy hour with half price sushi and some SERIOUS Kareoke. It is a trip! They are usually jammed, though, and you may have to wait in line if you don't get there early. Another great spot for brunch or lunch (or anytime, really) is Stella Blue in Kehei.
Some of our favorites for more upscale or 'Island' meals....Mala in Lahaina is a favorite spot for brunch or lunch. The location is amazing and the food even better. We also love Pacific O in Lahaina, and Humumu at the Grand Wailea. Our friends are big fans of Kimo's in Lahaina, though we have never been. Mama's Fish house is good, but honestly, for the money we weren't that 'wowed'. We have had an amazing meal at Sorento's on the beach in Kihei.
Okay, now I am getting hungry.... :) Have a blast!