Does a dual citizen of Canada and the United States need a passport?
I use the US passport only when going to the US (or if I have an international flight with a layover/connection in the US). So when traveling to the US, I do have to take both passports: one to enter the US, the other to come back to Canada. For any other destination, I take my Canadian passport and leave the US one at home. There is no need for both passports when traveling to any other country - and lets face it, Canadians do get better treatment all over the world. :)