N.K.
Definitely do the catamaran tour, it is awesome and I will do it every time we go back. I will have to find the name of the company we used and do an edit on my post to let you know. Some of the company's boats are too large and cannot fit back in the alcoves and what not, so the company you use is important. Also, any horseback riding is amazing in Kauai. Our tour took us through some desert/mountain landscape and also down by the beach. A luau is a must, of course. Kauai is amazing and you will have a wonderful time no matter what you do! It is so beautiful and relaxing, makes me want to move there every time we visit.