We were in Hawaii many years ago. Took a helicopter ride over the active volcano, visited volcano national park, walked up to the top of Diamond Head, Went to the beach on Maui - guys played golf, drove to the top of Mount Haleakala, attended a luau (very commercial), visited the royal palace, rented a car and drove around one of the island, I think it was Kauai....I'd have to dig out my pics to remind me of more!
My wife and I travel to Hawaii every couple of years. There are lots of things to do depending on your interests. We snorkel almost daily and spend much time in the water. On mauii I would reccomend going on Paragon charters to Lanai or take a trip with the Pacific Whale Foundation is there during whale season Nov to Mar. If time permits, the Old Lahina Luau is the best.
On the big island don't miss Volcano Park. At times yu can get very close to the flowing lava. There is no place else in the world you can experience this.
Kawai is a great place for a helecopter ride or a trip to the Grand Canyon of the Pacific.
Just lean back and enjopy the beaches and the people.
I'll have to triple that, the volcano tour on big island was really cool. We went with Vavoom Volcano Tours, which I'd definately recommend, the driver was really sweet and knowledgable. On Maui we went down the mountain on a bicycle tour with Maui Mountain Riders, that was really fun. On Kauai we took a ride out to keana beach and just hung out on the golden sand, because when in Hawaii do what the Hawaiians do. Hope that was helpfull