Currency question

Hi everyone, brand new on here and I'm sure this has been asked, but this is our first trip to Mexico. We're going to Desires RM and we were wondering about US dollars versus pesos, do we need to change over to pesos? Have heard a lot of places don't accept US dollars. I know DRM is inclusive, but figure we'll need some cash for tips, taxi and such.

We used American in Mexico at the the resort, only time we did pesos was on a trip to Playa del Carmen...exchanged at the hotel what we needed. Lots of small american for tips...BTW Mexicans consider the US $2 bill lucky if you can get some.