Hi, just my two cents. We did the Tulum Mayan ruins with a two hour stop at Xel-Ha. I wish that we would have just done Tulum. There is a beautiful beach there and I really regret that I couldn't stay to enjoy it. So beautiful can't describe it. Our excursion took us to Xel-Ha and we spent about two hours there and that was about enough for me. My boys went diving, but the waters were murky and they didn't enjoy it. But it might be a matter of personal taste. Here's a link to the ruins.
We will be on Radiance on May 14 on our way to Alaska.
Have a great trip.