Hukillau Lanai in Kapaa was highly recommended to us by people we trust but we couldn't fit it in. That's on the table for next time.
Bistro in Kilauea was quite good; open air and good vibe.
Bar Acuda is very good- make reservations ASAP.
There is a Merriman's in Poipu. We didn't go to Poipu but we ate at the original on Hawaii, and it was fantastic, one of my top 10 dining experiences probably. I'd try that out if you're going to be in Poipu.
You're probably flying in/out of Lihue, so I'd consider Duke's if a meal fits in your travel plans. The food is good, not great, but the scene on the beachside of the little cove there is really cool. We ate there before flying out.
We ate at Sam's on the Waterfront in Kapaa after flying in, and it was a nice pick for our arrival meal while driving on the way to Princeville. It was casual enough that we didn't feel too grungy coming off a long flight, and the waterside location was a nice decompression. Food was good too.
I will say that our view in Hawaii was to eat as much fresh Grilled seafood and sushi as possible, so any competent chef can deliver great fish if given great fresh fish to start with. Hawaii in general is stupid with the CoVID stuff, so when we went last year there were a lot of well-regarded restaurants which had not re-opened or which were on limited hours. This led to a bit of a scramble for everyone for the finer dining stuff. You should be able to find plenty of good Poke just about anywhere, though, and that's tough to beat in my book.
There is a fine dining place on the Wyndham resort which has just reopened or rebranded, which was getting really good reviews from the people we talked to, but the wait was always too long for us.
A couple of non-dining suggestions: make reservations for the Kalalau trail in Haena state park as soon as they open them (30 days out IIRC, and take whatever you can get) and since you're staying in Princeville, check out Anini Beach, a favorite spot for locals for snorkeling and sea turtles. Also, we had an open cockpit helicopter tour (at the time all heli tours were out of Lihue, they were about to start an option from Princeville area) booked which got canceled due to weather. I was really looking forward to that so I'd check that out: Jack Harter helicopter tours.
Here's a thread I started when I was going which has some good info:
https://texags.com/forums/54/topics/3197877/2#discussion 
