We just returned from Waiohai last Saturday. This was our 4 visit to Kauai and 3rd time trading into Waiohai. (We own 3 Marriotts and
DVC.) We traded our St. Thomas Marriott for Waiohai. If you have not already done it, call the resort and ask for an "interior facing view". This way you will face the beautiful, lush grounds of the resort. Some of the island views actually face the parking lot!

We also had an island view and did the above request. We received a great unit, interior facing, 4th floor with a glimpse of the ocean!
We have done many different activities over the years. What is it you like to do? If this is your first time be sure to plan relaxation time at the resort. First time visitors tend to overplan and miss out on the laid-back Hawaii experience. I would recommend you buy the book Ultimate Kauai. The advice in the book is usually very accurate. Our first trip was in 2000. It is interesting to see how many of the "secret" spots are not so secret anymore...a testimonial to the success of the book!
This last visit we spent very little money, cooked mostly in the villa and did our own excursions. We had a fabulous time! Food is very expensive in Hawaii, like the Virgin Islands. (Strawberries were $8.00/basket.) There is a farmers market in Koloa on Mondays at 12:00. Be there early with your cash and you can buy some delicious fresh island fruits, veggies and flowers. I bought a beautiful tropical flower arrangement for $10.00. K-Mart and Wal-mart have the best dairy prices. There is also a Costco. I always bring my own spices since they are lightweight and inexpensive to bring from home.
They have the soda mug for $29.00/each. (Pepsi products.) A great place for breakfast is Joe's on the Green. It is at the golf course near the Poipu shopping center. They have breakfast specials and a wonderful view of the golf course with the ocean in the distance. Food is very good. A new place we tried this time was The Shrimp Shack in Waimea. Wonderful shrimp at an outdoor shack. Our favorite place for burgers is Duane's Char Ono burgers between Kapaa and Princeville on the NW shore. The burgers are really good, but the surroundings are unique. It is an old fast food type place (no restaurant in Kauai is really "fast food" LOL). You sit outside with chickens meandering around and the view is of spectacular jagged pitons/mountain peaks that look like they were draped with green carpet.
If you do one tour, I would take a Napali Coast boat tour. Do not take an inflatable, too bumpy. Take a sailboat or fishing type boat. Try to find one that leaves from Hanalei. If you take one from Port Allen you spend most of the time getting there and the ocean is much more choppy on the west side of the island.
Feel free to PM me if you have lots of questions.
Have a wonderful time.
Aloha,
Lisa