I was on the second of the 7 day western cruises. I was VERY disappointed in the Tulum ruins excursion. If you are going to see the ruins (they are worth it) don't use the ships excursion unless they have changed the vendor in the last few years. We had a horrible 1hr 20 minute ride with soggy sandwiches, then the "private" beach - well that was a long drive through a garbage dump to find a beach so loaded with cruise people from many ships that there were no seats, the showers were forever blocked, and the bathrooms better left undescribed. My companion and I complained bitterly and were reimbursed 50% of the cost. The ruins themselves are magnificient. Just not with that vendor.
good luck!
Padalyn