As Racerguy said, "some financial institutions refund you any ATM fees". We have bank accounts with Etradebank and it does. Also you can get cash back at places like Wal-Mart if you use a debit card. If you are not getting reimbursed for fees then take out as much cash as you can at once, $500 if possible, since the fee is the same for $20 as $500.
Watch your credit cards in Canada. If you can do a short test trip then use each card at least once and see what extra fees come on your statement, if any. Citiback (AT&T Universal) charged us a higher exchange rate and charged us fees for Canadian usage. American Express was better, but not taken everywhere. Capital One was great, so we use it as much as possible in Canada and any online purchase from other countries (like Hong Kong eyeglasses, which are an amazing deal). Getting cash in Canada can sometimes be tricky, not all ATMs support the US ATM networks.
We use $100 or less in cash most months, instead using on credit cards we pay off every month. With the points we get gift cards for restaurants, Amazon and Wal-Mart instead of airline miles. I do mean credit cards, we have more than one we use regularly and we track the various deals on points to maximize them.

Rod,

Welcome to the RV Dreams forums.  You have definitely found one of the best sites for your research.  We all welcome your questions and comments as we all tend to learn along with each of the other members.

If you are a veteran, look into USAA.  While they used to be only for officers, they've since opened up membership to all veterans.  I haven't begun using their financial services yet, but several on the forums have given them good reviews.  They will initially "charge" an ATM fee but will later refund that fee back.  Plus, if I understand the others right, most all the transactions done with them do not require any face-to-face transactions.

Terry