Yes, I have been to Argentina. 3 times. The last time, you are right, the ATMs were not the answer, because the money changers on Ave Florida had the best rates if you brought US cash. As for otehr countries, I have only been to another 153, so you may have more experience that me.
I am not talking about YOUR bank charging, I am talking about the FOREIGN ATM charging. I have two debit cards that do not charge me for foreign ATM use. I am not sure about the other one, as I don't carry that debit card around.
FYI, I have internet access in most countries you are likely to want to visit, and many you don't with T-Mobile. Or you can plan ahead and download the maps on your phone using MapsMe.
But I don't think I have ever used my phone to find an ATM, they are just about everywhere.