Canada is a foreign country, BUT EXTREMELY FRIENDLY. If you were in business in Florida would you accept Canadian money for your goods and services? And if you did would you give the current exchange rate? You are talking about traveling all the way across Canada to Alaska.
To answer your question, In my opinion:
Since both credit/debit cards are accepted nearly everywhere, and Canadian currency is accepted everywhere, it really depends on how much you plan on spending and how much you want to save.
Nearly all cards have a 3% international fee applied to each transaction. You need to check with your bank to see if they charge the fee. If they don’t, then by all means use the card.
If they do charge the fee, then inquire if they have a reciprocal agreement with any Canadian bank to allow ATM withdrawals without having to pay an ATM fee.
We use BOA and they have an agreement with Scotia Bank that allows us to withdraw cash without the fee, and we get the current exchange rate. We have not used a card for purchases in Canada since 2005; the 2004 trip taught us a lesson, and we go every year. Now we just go to Scotia Bank and withdraw cash.
As you can see that is a savings of $30.00 per the thousand and I need it much more than the banks. Our trips to Canada over the past 10 years has averaged about $6,000 per year.
And depending on what you are driving you could spend a couple of thousand dollars just on fuel, camping, and food getting round trip through Canada. Example: a motorhome getting 8 mpg will cost at least $2,000 in fuel.
Go and enjoy. We have been 3 times.
You can see my trip logs at the website in my signature. They include the prices at the date incurred.