My wife and I honeymooned in Kauai. We did a week at Princeville, which I would highly recommend on our 2003 visit, and I am told it is far better all around now. Hanalei is an awesome little town, and there are great beaches every few hundred yards. The golf was good when we visited. I enjoyed the Prince, although it can be penal, and have heard great things of the recent work. My wife (not a golfer, really) played Makai with me and it was both beautiful and playable. If you enjoy hiking, there are some incredible spots, such as Ke'e beach, where you can walk down the Nepali coast, which has no roads or inhabitants (except a bunch of hippies that have life truly figured out). We also took a boat ride along the coast, which is among the most beautiful spots I have seen. The rain on the north coast was not an issue when we went (August). My wife and I felt the North Coast was perfectly quiet and serene for our needs, with just enough in the way of restaurants and shops (totally non-commercial, though).
We also stayed for a week at the Marriott, which is closer to the airport (SE corner of island) and a bit more of 'civilization.' While not quite as quiet or luxurious as Princeville, it was in a nice spot and had a great property. I really enjoyed one of the courses there (one is substantially better), and again played the other (Mokihana, which they may have closed) with my wife. From that location, one of our favorite activities was visiting Waimea Canyon, which is truly breathtaking. We visited some of the beaches on the south coast (Poipu beach, et al) and they were also beautiful, if not as remote as up near Hanalei. I played Poipu GC, and had fun, but besides the seaside views did not consider it worth full freight. I do wish I played the muni on the east coast instead.
I've been to the other islands in Hawaii on other trips, and would pretty much say you can't go wrong...Maui is probably the safest bet overall, but the big island, Kauai, and Oahu all have much to offer, depending on your priorities. I regret never having gone to Lanai. I understand it is a very easy trip (for the day, or a few) from Maui, with good golf and nice resorts. Congratulations, and enjoy!