Exchange rate also comes into the picture for Canadians
....that's for sure. With the Canadian dollar down an astounding 20 cents (exchange cost to the guy on the street), this is a massive incentive to go instead to Mexico, Spain, etc...
The Canadian dollar is really a petro currency, so it is almost 100% correlated to the price of oil and our interest rates (interest rates attracting foreign investors). One way to try and justify the huge differential if you are a Canadian RV snowbirder heading to the US, is to consider the off-set gas prices in the US now vs. when the Canadian dollar was close to par, and reconcile that difference against all your (planned) in-USA expenses...
Once the Canadian government (read: our banks) raise interest rates (soon to come), you'll see the CAD climb again (resisted only by the continuing falling oil $$ commodity).