I will add a vote for using your ATM card. We have always used our bankcard at an ATM in the airport when arriving at a foreign destination. When we arrived in Peru, we did not find an ATM right away in the airport, but just asked our taxi driver to take us by a safe bank with an ATM to withdraw money. He was happy to do it. We have used our cards in Asian countries, Caribbean countries, and South American countries with no problems. I do suggest calling the number on the back of your bankcard and telling them you will be using the card out of country and the duration of your trip. They tag your account with the information so it is not frozen as a possible compromised card.
I have compared the rates we are charged on our bankcard and what I can get from the bank or the exchange counters in the airports. The difference is so small that we choose the convenience of using our cards. Just remember, you need to stock up on cash if you are going to destinations with few or no ATM's around. We did not see an ATM for several days while on our A mazon cruise, but that is what we expected.