Our parents in law treated us to a really nice vacation at Atlantis (in Bahamas). My MIL every year swims with the dolphins. Honestly being on this nice of a vacation, you don't need the "extras". If your family wants you to be part of the dolphin experience just explain it is not "your thing" and you can always watch and cheer them from a distance. We also met up for a number of meals.
Hawaii has been one of my dream destinations since around 6th grade (that, Greece, and Costa Rica), but as I now live on east coast, doubt I'll make my way there. Enjoy it! Depending on what Island or Islands you are visiting, I would read up on it; there are many unusual and beautiful beaches and locales. If you are a LOST fanatic you can try to visit some of the places used in filming. The lower elevations have many introduced exotic species of plants, while if you go up the mountains you will be able to glimpse species of birds, insects and plants that are native to the Island.