I just realized I failed to thank everyone for the advice regarding my recent trip to Cancun, which included a day on Isla Mujeres.
My daughter really had a great time doing the dolphin swim and the shrimp ceviche at Bujo's was some of the best I have had. I don't know that I prefer it to Cancun, but it was a great day other than not being able to use a damned chair or umbrella on the beach.
I would definately go back to spend a day in the future. Hell, I'd go back just for lunch at Bujo's!