I wouldn't do either. You can get pesos from your bank. Just ask. Then bring your debit card and use the atm down there to get more pesos. Converting to US to convert again is just wasteful because you pay 2 exchange fees. And besides, they're Mexicans, they want $US about as much as us Canadians want $US. We'll take them if that's what's offered but a $CAN is a lot easier to spend here. Same as a peso is a lot easier to spend in Mexico. When in Rome...
Don't bother taking US $$. You're wasting money exchanging to US $. You can buy a small amount of Pesos from your Canadian bank or a currency exchange place (airport, mall, etc.) in Canada then withdraw Pesos from a BANK ATM in Mexico or even an ATM at your hotel. You need a four-digit PIN though, not a six-digit. I got the best exchange rate (even after the Plus System fee) from a bank ATM. I got the second best exchange rate using my VISA card. My local Canadian bank (RBC) gave just an OK exchange rate when I bought Pesos prior to leaving Canada. I won't be doing that again. Don't use US dollars, you are not going to the States, you're going to Mexico. It is always best to use the currency of the country you are in, in my humble opinion.
I agree with bringing money from US or Can. We heard that they prefer to be tipped in something other than pesos since US or Can currency is worth more.
Some things like tours are expected to be paid in USD. My trip to Xcaret and our airport transfer can only be paid in USD. Does Steve take Pesos for his booze cruises? How about club excursions at night? If I recall they wanted USD. So it all depends on what you are doing. If it is just pocket money, take it out of the ATM when you are there. But for other things the peso might not be the correct choice. Do not take CND, nobody wants that
Nobody complained about being tipped in Pesos. I tipped nearly exclusively in 20 and 50 peso notes (had a few US $1 bills, but not many). Given the choice of US$1 or 20 pesos I think they'd take the 20 pesos (about US$1.40) unless they can't do math. I agree some things might require US dollars, but I didn't encounter any during my trip. Everyone was quite content to take my Pesos or my VISA card. I agree that nobody wanted Canadian $ however the driver from the airport to Temptations obviously didn't refuse them since he had CDN $5 and $10 bills visible in his tip cup. I'm sure it's a pain to exchange them but they weren't refused.
We've always taken USD. We have a friend at the bank that gets a better exchange rate. We try to stick to 20s and a lot of singles.
Yes, but the rate isnt great (the company that own the boat set the rate), better to pay with USD for the booze cruise. Credit cards are also accepted but there's a 5% fee - again not in my control.