Kauai is not the best-known nor the most commercial of the Hawaiian islands, but it is the most beautiful. It's a little harder to get to than Oahu or Maui or the Big Island, but well worth the effort. The Kauai Marriott is beautiful and accommodating with the usual outstanding Marriott service. One small nit: its proximity to the airport can sometimes produce unwanted noise, but we didn't notice it nearly as much as we feared we would.
Be sure to have dinner at The Beach House on Poipu, and try to plan your dinner to occur during sunset. Unforgettable!
And do not leave out a helicopter tour, preferably with Blue Hawaiian. Book your tour in the early morning, when you're most likely to get good weather on Mt. Wailele. If it's clear, they'll fly you into the crater where you will see literally hundreds of waterfalls. The most pristine sight you may ever see. Aloha!
I agree with the comments about the Kauai Marriott Beach Club. Great, relaxing place to stay. We find it fun to sit on the balcony at night and watch the planes coming in to land at the airport while we look out over the waves in the harbor and hear the sound of the 'surf'.
The Beach House at Sunset is definitely a MUST! We celebrated our 30th anniversary there with a gorgeous sunset, but you may need to make your reservations before you even get to the island.
For good seafood and convenience, you can't beat Duke's restaurant on the premises of the hotel, and you can charge the meal to your room to collect Rewards Points!