Arthurrs,
I truly believe that the Big Island is one of our hidden American treasures. Check out other threads on things to do there. Find a way to go up to Mauna Kea and the Observatories... especially if you can do the free Keck Observatory tours... love it... and then the star gazing in the evening.... Lots to do away from Kona.... and so memorable.
OK, now I want to go back!