Your own bank...they will give the daily rate with no fee if you are one of their clients. Any other exchange place will take a commission on your exchange in the form of a bad rate or even with a fee. I work in a Casino that deals with US currency exchange and I hear people complain all the time about our rates(Bank rates by the way) because they think they got a better rate at one of those booths outside...until we explain the rates to them and they realize they got taken for a few bucks....just use your own bank...it's the best way to go...and don't wait until you get to the States...they convert it slightly differently and not to the Canadian's advantage I can tell you!! Have a great trip!!!