How did I miss this thread???
When I want to Kauai - eeks, 10 years ago, now - I rented a car and kind of drove myself around - doing some short hikes in the Canyon and checking out the sights. I was there only a few days, and ended up meeting someone and going mountainbiking (and excercise in futility - the tire kept gunking up with red mud and stopping me cold every 20 feet when there was too much to pass through the fork!).
I did do one "touristy" thing - and that was take the Captain Zodiac boat ride around the Na Pali coast. It was spectacular. And the really cool thing was that they had a hydrophone on board, so we cut the engine of our boat and drifted and put the 'phone in to listen for whales. It wasn't prime whale season, but there were a few critters around that we could hear. Was very neat.
Have fun when you go and take lots of pictures!
2007 Seven ID8 - Bontrager InForm
2003 Klein Palomino - Terry Firefly (?)
2010 Seven Cafe Racer - Bontrager InForm
2008 Cervelo P2C - Adamo Prologue Saddle