Grand Cayman is really the one island that is hit or miss. If you do port, you may be alongside seven ships as I was one time. This means a very crowded town...If you have an excursion you want to do..pre book with the ship,or say with Capt Marvin, a very reputable tour operator, for Stringray City.
You can go the Hell, visit the turtle farm,or window shop...On one cruise, due to rough seas, the Captain, actully ported on the other side of the island,and we bussed into town, which was interesting..you would swear you were in Florida
I hope you get to see the island..