You should be able to take two excursions. As we will be in Grand Caymen (We are sailing on the Enchantment Sept. 8th and will be in Grand Caymen) from 8A.M. til 5P.M.
We have decided to go on the Cockatoo Catamaran ourselves because you will get to sail around the island do some snorkeling , plus you get to go to stingray city.
Hope you have fun,