me, my husband and our little toddler visited riviera maya last week.
mistakes we made are:
-not taking single dollars and not converting dollars to pesos, the consequences are: you are giving bigger tips like 10 dollars and also for example paying 50 dollars for something worth 500 pesos, you definately loose.
-don't use your visa credit card because it charges you 3% for international purchases, check with your credit card and your debit card.
-our shuttle service at the airport is turismo mundial, so when we got to the airport after customs we saw a guy witha uniform that says turismo mundial, he immediately took us to the timeshare guy who claimed he is not a timeshare person! he offered us two xcaret tickets for 40 dollars both if we go visit a hotel in cancun that is 25 minutes from our hotel, we accepted. it ended up being one hour and 15 minutes away and it was a timeshare! so YES we got screwed, and xcaret wasn't a good choice for a family with a toddler.
after you pass customs DO NOT talk to any person even if he has a badge with your shuttle company name. GO OUTSIDE and you will find someone holding a carboard that says your name if you have shuttle service reservation.
i really don't want anybody to make teh same mistakes i made.
also if you are staying in riviera maya don't waste your time going to isla mujeres, it is a long drive to cancun then you gotta take the ferry, we did the carribean fun day tour from cancun-discounts.com and it was bad, waste of time and money.

You have given the travelers some good advice. I'm surprised you made these mistakes. Many Yahoo posters warn travelers to Mexico of these same mistakes.

We loved Xcaret. I'm surprised your toddler didn't enjoy the dolphins or the beach.

Capital One doesn't charge a fee for international purchases. Most credits cards do.

It pays to do research when you travel out of the country.

Sounds like you learned valuable travel lessons for future travel to other destinations. Sorry you had to learn the hard way.)