How much Canadian currency will I need, e.g. for things like transportation between the airport and downtown?

As a Hostelling International-American Youth Hostels memberš, I'm entitled to commission-free currency exchange service from Travelex.

In Vancouver, I believe the best exchange rate can be obtained at BC Liquor.

šAll Hostelling International members, including Hostelling International Canada members, should know about these discounts:
http://www.hihostels.bc.ca/discounts/discount3.htm