We spent a month on the Big Island. If you are going to visit its great but the beaches are hard to find and some require some "long walks". It was nice there and the tourist types were not as bad as the other islands, so its a trade off. I took my mother (to watch our kids so dad and I could "romance") and that made all the difference in the world. She also went parasailing and in a submarine.
All in all I think we will go back to the Big Island. Anyone know of other activities or "lost" beaches?