When we had a 2 day stopover in Hawaii on our return from our USAF assignment in Guam we rented a car so we could drive around the island and stop wherever we saw something interesting. There was also a visitors guide that we were given which listed sites to visit along the way. Since we were traveling with small children, we did not visit the historical sites which I would have greatly enjoyed, but we did spend a very enjoyable afternoon at Paradise Park. I don't know if it is still there as this was over 30 years ago, but it was a fun tropical zoo / amusement park for both adults and children.
Still wanting to go back on an adults only visit!