Without going into detail-
Lahaina Grill- Excellent service, really, some of the best I'd had in a restaurant in years (though I'll note that my girlfriend and I were impeccably dressed, so that might have had something to do with it). The food, however, was a bit of a disappointment- portions were huge, but the dishes were crudely flavored and composed- my mother (like me, a native New Yorker) would call this "suburban cuisine". My porkchop was underdone (rare enough in the middle to warrant sending back, but I decided against it because it was unnecessary with such a huge portion); my girlfriend's lamb chops were overdone (she asked for medium rare- received decidedly medium). The veggie sides and sauce (really, demi-glace) with our two dishes were virtually identical- a big no-no for a top restaurant in my opinion (especially when the one of the two veggies were "baby carrots" of the fresh-out-of-the-bag variety. The (French) Maui Onion soup was excellent and intensely flavored. Wine list was strange, as it was at all the Maui restaurants we ate at- we had a glass of the Turley Zinfandel ($26) which was fine and fairly priced, but the wine list both by the glass and bottle was almost exclusively American and of big, high alcohol fruit-bomb wines. I get that subtle wines go badly with the "bold flavors of Hawaiian cuisine", but there's a line between bold flavors and crude cuisine, and IMO, this crossed it. We skipped dessert.
Pineapple Grille- The food here was virtually identical to Lahaina Grill: big portions, bold flavors, crude presentations. I liked it here a lot more though- first off, the prices were about $8-10 lower per entree, across the board, which reflected fairer value for what was given; second, the atmosphere here was more country-club suburban (its at one of the Kapalua golf courses) and I felt the restaurant was more honest, in that it didn't pretend to be something that it wasn't (haute cuisine). An appetizer of Crispy Duck spring rolls were piping hot/fresh and crispy and delicious. My girlfriend's steak was huge, but of middling quality (I think the menu claimed it was local beef, but I know standard big-Agri USDA Choice when I taste it). My boneless short ribs were soft and flavorful, but my "korean-influenced" sauce was too close to out-of-the-bottle Hoisin sauce for comfort. I sound overly critical here- I'm picky about my restaurants, but this place had a very winning quality about it. We ordered our wine off the half-bottle list--note that Lahaina Grill had a virtually identical wine list, which struck me as very odd (like, about a quarter to a third of the bottles were common to the two lists). Again, we ran into the "fruit-bomb-only" problem, and Pineapple Grill also prides itself on pouring as many wines as possible with high Wine Spectator ratings--its middlebrow oenophile nirvana, but if you care a lot about your wine its a little off-putting. We settled on a Novy Syrah, 2005, and it only served as further evidence to me that I don't like the winemakers at Siduri (same winemakers, and this had a Siduri-esque ~15.5% alcohol).
We had a pineapple upsidedown cake for dessert, and it was spectacular, drop-dead delicious, etc etc. It's served with a delicious caramelized pineapple/coconut/I-think-a-bit-of-honey sauce, and comes with macadamia nut ice cream and shredded filo dough, so you get almost a baklava-type effect with the sauce. Showstopping stuff, and so good we stopped by on a second day to order it again at a snack while eating on their outdoor deck and having a cocktail (its a lovely deck, btw).
Those were the only two restaurants I feel like writing detailed reviews about. But some short notes:
Hula Grill- Best option on Kaanapali, but that's damming with faint praise. I'm too harsh, though. It's fine, in a functional, mass-dining kind of way, with notably fresh ingredients. I can't whole-heartedly recommend because my girlfriend's fish and chips (when we were at "The Barefoot Bar" for lunch) were a few minutes past their prime by the time they reached our table, and that's a cardinal sin with fish and chips.
We avoided Leilani's, also at Whaler's Village on Kaanapali, but based upon the food we saw (and it has a ton of outdoor tables), I couldn't recommend it.
So too with most of the restaurants in Lahaina proper- I stuck my head in Longhi's and it looked miserable. YMMV, of course.
W/r/t lunches and snacks, I had excellent sashimi and poke at both the Maui Fish Market and the Miyaki Fish Market, with Mikayi being the better of the two- the fish was breathtakingly fresh, and it was a great option in the general tourist-hell of Lahaina proper. Miyaki is so close to Highway 30 that there's no excuse not to stop in for a sashimi to-go; hell, there's even free parking.
Didn't get a chance to try Honokowai Okazuya, but its in the same strip-mall as Fish Market Maui so I peeked in- it looked legit enough.
We stopped in the Olowalu (sp?) General Store en route to snorkeling at Olowalu Beach; the plate lunches looked great and the people in the store (amazingly, not tourists) said that they were delish- I didn't try (I was about to spend 2 hours in the water) but I would definitely recommend stopping in for a snack, as it was refreshingly non-touristified compared to all the stuff b/w Lahaina and Kapalua.
A couple I chatted with in line while waiting to check out, whose food instincts seemed good based upon the rest of the conversation, reported a very positive experience at the Plantation House.
Lastly, we went to the Old Lahaina Luau, and the food was middling but adequate. The show was good, though. Stick to the mat seating if your joints can handle it- you sit in front.