Can't you leave your money outside the country and only use them whenever you are outside your country?
The US dollar is probably the most widely-used especially on the internet, but from day to day I (obviously) use the Canadian dollar the most.
I have to go with the U.S. dollar, but I'm not happy with how the Canadian dollar has been climbing against it recently. 90% of my income is in USD, so the weaker the Canadian dollar, the better.