That is very disappointing about Kauai as I personally believe it is the most beautiful of all the islands. With that said Kona is the cutest little town on the big island. I absolutely love Kona and I think it is well worth the tender ride. Make sure you go to The Kona Inn for a Mai Tai. They are the best I have ever had but if you have two be prepared to take a long nap after.
Kona is the perfect port to do it yourself. When you get off the tender platform head down the coast line. Lots of shops, restaurants, museum houses, local items etc. Pick up some Kona Donkey Balls they have about 100 different flavors and are delish.