Hey -- Just an update. Continental's Web site said the airline would charge us $150 each way for oversized/overweight bags. We had two oversized boxes. One of them was over the 50 pound limit.
As it turns out, the airline rep that checked us in for the flight to Vancouver only charged us $100 total. The Air Canada rep for the Yukon leg charged us nothing, instead of the $50 per bag on the Web site. On the return trip to Tampa, the rep charged us nothing. I didn't ask why. It goes to show that it really depends on the rep you get when you check in. Instead of looking at at least $500 for moving the bikes around, we only paid $100.