Pick up the blue books from wizard publishing
http://www.wizardpub.com for the islands that you're going to visit.
We got Maui Revealed and we were able to have a great trip on a low budget because of all of the advice... it was like having a personal tour guide.
After my time there, it seems that doing guided tours is an expensive way to have experiences that are often available for free.
If you really want to see Oahu (Pearl Harbour was cool), visit it first. We did Oahu after Maui and were really disappointed with it, especially Honolulu.
Sounds like you'd have more fun on the less touristy islands - Maui, Kauai, Big Island (Hawaii) - exploring the jungles, terrain and beaches.