Suzy, wecome to Cruise Chat! We loved the Chacchoben Ruins. We booked the excursion through the ship and were not disappointed.
Like you said, everyone enjoys different things. I have heard great things about Tulum. But, I believe, it is a long trip from the port and we didn't want to be gone that long.
We are so hooked on cruising, and I just know you will have a wonderful time, as will your Mom and sister!