On my trip to and from Alaska, I found that banks offered the best exchange rate. Always good to have some $CN with you. I found that my US Dollars were widely accepted for CN dollars one for one because of the then current exchange rate, but that rate changes often.
I don't think that it will ever happen, but I'd love to see us follow the lead of Canada and use $1 and $2 coins. "Loonies" and "Toonies". They physically last a lot longer than our singles.
The only problem I ran into was at a deli. Lunchmeat was sold by the gram and I didn't have a clue. So I ordered 8 slices. And I still don't know the ounce/gram conversion.
The other thing that surprised me was gas stations with attendants that pumped the gas, and it wasn't optional. But since its sold in $CN/Liter, you really don't know what you're paying or how much you need, so you just "fill it up".