We've never carried large amounts of cash. Years ago we did the travelers check thing along with a few hundred dollars US cash. In later years we used our Scotiabank debit card at BOA ATMs (no ATM fee for Scotia customers) to get US cash plus used our CDN credit card for many purchases.
But now (last 5 years or so) we have an account, check/debit card and credit card at a US bank. Throughout the year whenever the exchange rate is good, we go on-line and buy US dollars for deposit into our USA bank account. When we are south we use our US bank issued check/debit card for cash (no fee at some ATMs and the bank reimburses the fee at all others) and our US bank credit card for most transactions.
Since we have on-line access to our CDN and USA accounts we can and do continue to do our banking (including transfers between CND and USA accounts) while we are away from home. We have no need to set foot in a sticks and bricks bank. We can deposit a check simply by taking a picture of it and sending it to our bank on-line.