Welcome aboard, Wanda!
Earlier this year, I took a ruins Port Adventure in Cozumel and the same adventure you're considering in Grand Cayman. I can highly recommend them both!
My adventure in Cozumel was not the Tulum ruins, but the Cozumel Ruins and Beach Tour. I loved that we were able to get in some history and learning at the ruins of San Gervasio, but then got to head to the beach for a relaxing couple of hours at a beautiful beach club to cool off. The Tulum ruins are amazing, I've heard, but they are a much longer ride to get there, whereas the San Gervasion ruins are not far. Either trip would be very educational and a lot of fun, but be sure to bring bottled water and wear light clothing. It is very hot at the ruins!
The Grand Cayman Island Tour is a wonderful adventure. We stopped at the rock formation known as Hell. These rocks are really interesting and very strange sitting right there in this tropical paradise. The stop here is short, just enough for a few photos and a stop into the souvenir store on the property. They will even stamp your passport with a stamp from Hell.
While that stop was interesting, the best part of this tour is the time you'll spend at the Turtle Farm! If you're only interested in the Turtle Farm, you might be better off on the
Boatswain's Adventure Marine Park tour which allows you much more time to explore the farm in depth. My son loved climbing into the tank with the baby sea turtles and I loved wandering the premises learning about these amazing creatures. We grabbed a quick bite to eat there too, where I tried a conch burger for the first time. Delicious!
I hope that helps as you continue to plan your adventures, Wanda. Let me know if I can help with anything else before you set sail!