Something dry for y'all to do, if you haven't been to the archeological sites, San Gervasio is really a nice late period site. No large impressive temples, but a very interesting and educational way to spend a couple of hours together. Unless she's creeped by lizzards, there's gobbs of 'em there!
Breakfast at the Museum is always a must for my wife and I on a off-diving day, it's kind of romatic on the second story deck having breakfast with the locals. The museum is pretty cool it's self, go downstairs and to the back of the building, there's a mayan house back there and an older gentleman that tells you about the daily mayan way of life, I stop in and see him every 2nd or 3rd trip for a "refresher course"
Taking the ferry to Playa del Carmen for some shopping and people watching is a good afternoon to spend together also. It breaks up the scenery and gives a different perspective on the channel.
just tryin' to help brother!