Just got back from one week at Poipu - info. posted earlier by others helped me so I thought I'd update for others. I took my family and these were our results.
#1 Plantation Gardens - been there forever - at least 35 years. Fish is local - many other rest. ship theirs in. Two versions of Ahi grilled over Kiawe wood rocked. One with fruit salsa, and the best with balsamic vinegar. Oriental pork tenderloin was a winner. The macadamia crusted Ono was a little over cooked. Try the Banana Lumpia for dessert.
#2 Roy's: For the total blowout try the prix fix 5 course with matching Sake's. I am not a Sake fan, but the pairings with the first three courses were tremendous. A scallop course, a salmom skin salad and a spicy crab cake course. The main course overpowered that sake, a split between some rib eye and some miso seasoned butterfish which is spectacular in this tasting or as a stand alone dinner.
Get reservations. This place gets slammed even mid-week. By the time we left one night the place was full and there was at least another restaurant full of people waiting, many with kids, yikes.
#3 Tidepools: Expensive, but the crab shitake opah wtih asparagus was very good. Also, try to get reservations later in the evening. Even tho this was an expensive restaurant, our 6:30 reservation encountered too many tired cranky kids in this Hyatt resort restaurant.
Bring your appetite to the Sunday brunch at the Ilima Terrace in the Hyatt. Very good variety, from sushi to tempura to rack of lamb and fresh shrimp. The winners for dessert included macadamia nut black bottom pie and some coconut chocolate truffles centered with very dark rich chocolate.
#4 - For a quick lunch, sandwiches made to order at Brennecke's deli were good value and local. Also good locally was the Chili Poke from the Big Save grocery in Koloa.
#5 in Tomkat's Grille - food was OK but stay away from the lunch plate - boring.
#6 Hanalima Baking Co. is a real bakery with bakers hours - 6am - 2pm located across the street from Kauai Community College. Others noted their scones. We loved the cinnamon rolls. They tend to run out of stuff early so the early bird gets the dough. Next door you can get your Spam Bento fix (yuck) but the place was busy. Better local food is the loco moco - white rice - fried egg - a hamburger patty and brown gravy.
Last - if you have a kitchen or fridge - visit the Lihue ranch market located in the Parking lot of the stadium. Great papayas - the most expensive was $1. Fresh passion fruit 4 fruit 4 $1. The advice of others to be there a little early is smart. The white pineapple was not cheap (called Sugar Loaf) but it is low acid and like candy. The place is busy and favors locals. Fruits were esay to get. The lines around the available veggies resembled a shark feeding frenzy.
Hope this post helps you have a better trip. To put on real shoes after a week in Paradise was painful but I owe, I owe so back to work I go.