The helicopter ride over Kauai is well worth the money. You see where the island formed, numerous waterfalls, the rainforest, where movies were filmed, and the picturesque Napali Coast. You won't experience any of this unless you are a devoted hiker and in tip-top shape. None of this is accessible by car.
We also island hopped. We were not impressed with Honolulu (too commercialized and fast paced). We wanted to see the infamous Waikiki Beach and Diamond Head. Once and done. We would not return. The bus ride was an experience from hell. It is an eight-mile trip that took 1.5 hours.
We ventured to the main island of Hawaii to explore Kilauea -- a must see. We took a helicopter ride over the sleeping giant -- a spectacular sight. It was not erupting when we were there, but they had experienced an earthquake three weeks prior that was a 5.5 on the Richter scale and waiting for the Fire God to burst at any time! The smoldering crater looked prehistoric. The lava flows from over the years were never ending as they made way to the ocean, taking roads, homes and anything in the way. It was an eerie but thrilling experience.