Would appreciate your opinion please! Our family is going to PDC in April with our two boys (ages 9 and 12). Given the short attention span of kids, I am considering going to Coba (and maybe Tulum on the same day?) rather than Chichen Itza. I've been to CI (20 years ago!) and love it. But it is such a long ride and I'm thinking that maybe Coba will keep their attention more since they can climb and ride bikes. Is enough "uncovered" at Coba to give them an appreciation for the Mayans?

Yes, Coba is a very nice site. It is spread out through the jungle so your boys will enjoy the ride. Go early in the morning so that it's not too hot or crowded.

As far as going to PDC in June or July. I spend both months there and it is hot and muggy. I rarely stay at the beach past mid morning because of the heat. We do get some great thunderstorms sometimes which I don't get a lot of here in the states. But, if you stay under a palapa at the beach with the breeze off the water it's not too bad and the water for swimming is great.