I have used my Capital One 360 ATM card in a dozen countries to withdraw money from foreign ATMs. (This is NOT a credit card) The transactions are WITHOUT FEES and they post at interbank rates!
I love that ATM card.
Regarding taking US cash: I usually have US$100 in nice bills in my billfold. Upon arrival in Budapest once, the ATMs were out of cash! I was so happy to have US$ to exchange so that I could pay for my taxi.