I was able to use Canadian money there (bills only, no coins). You will get your change in pesos, though.
Don't know about travellers cheques, as I didn't bother with any, but your hotel should be able to cash them for you.
I've changed CAD in Travellers cheques and cash, No problem.....if you go away from your resort, and go out into the countrie....chances are they will not accept it ....in cash or travellers cheques.
Thanks Doug and JJSK...
I have been looking for this info for a couple of weeks now. I can't believe how fast I received a reply.
I lucked out finding this site this morning. I will spread the word about it.