We use both...when we take trips to the US we save all of our ones to take to Mexico and then I also buy some Pesos before we go. D
One other point - just make sure that you do not tip with US, Canadian or any other countries coinage - they cannot spend or exchange foreign coinage for mexican currentcy !!
you buy pesos in Canada ? I found it is much better exchange rate when you exchange it down there ! just never at the hotel . on the street is ok but their banks are the best rate .
We just get $100 in $1 USD bills before we leave home. Handy during our week plus when you get that from your local bank they will usually be in good shape. I just put 10-15 $1 in my swimsuit pocket before heading to party pool. Wet $1 work fine too! Also works great if you want extra beer, water, etc in your room frig. Note and couple bucks in the frig work just fine.
I've brought US bills in the past, but in reality pesos are far better for the folks down there. Since we have to convert them anyway, may as well go directly to something they can spend easily. If you're from the states, may as well stick with US dollars.
Just curious. Why cant they spend or exchange U.S. coins. I never have any trouble spending or exchanging them. Even while in Mexico.