There is lots of shopping and tourist fare at the pier area. They have dancers that entertain etc., but it does somewhat resemble a zoo. I went on a tour of the ruins and it was a very hot day, it was wonderful but could be taxing on your wife. My Hubby and the kids did the coral reef snorkel and loved it but again it may not be appropriate for your wife depending on how far along she is.
Our table mates at dinner rented golf carts at the pier and took them into the fishing village of Majahual and thought that it was charming. They felt they got a little taste of true Mexican culture as opposed to the whole tourist thing at the pier. (You can also take a taxi for about $5 USD and that may be easier on your wife if it's a very hot day.)
I'm sure no matter what you will find some way of enjoying it there.
Enjoy your cruise!!!