I've been out to Kauai a few times, as my father has gone there every year for business since the early 80's.
I haven't gotten to play Puakea or Kiahuna, but I've played Kiele and Mokihana, Poipu, Princeville, and Wailua.
Puakea and Kiahuna look more local-friendly, and to me they seem to be better golf courses (solid strategy without the semi-playable flash and ornamentation) than the others.
I'm a big fan of Poipu, but alot of it's fame is it's connection to the stars of today that play in the Grand Slam, but it is a solid design, with the crescendo of the last few holes being good enough to compete with Kapalua.
Kiele was fun, but the signature 16th was perhaps the worst hole on the course to me. Beautiful yes, but there wasn't even a spot to lay up! I don't remember Mokihana very well, but compared to the "press" (perhaps internally Marriott-generated) Kiele gets, I seem to remember it being better than I expected.
Princeville is a course you must see once if on Kauai, but after that, the jury's out. It's Jungle golf to the max, and if you ever lack the confidence you can hit the grass (as opposed to the deep rainforest), then lay up. Potentially not worth the big money either, as good shots are only sometimes rewarded.
Wailua was great fun, in a minimalist way. The course conditions are nothing to get too excited about, and either are too many of the holes, but the par 3 on the ocean, and the several holes starting the back nine that test your wind play are some of the best on the island. Who needs the bright green bermuda and the well-built red clay bunkers when you have wind, waves, and for once a low price tag....