We recently spent a lot of time in Spain and from our experiences we can say that for paying for groceries or other credit card purchases the most inexpensive way to go is to use the USAA Visa card.  We read some horror stories of surprise charges with other financial institutions and were relieved to see our charges on the USAA card used the correct (actual) exchange rate.  Read the fine print on your card agreement and know before you go.  Some unscrupulous merchants in some Euro countries have programmed their card readers to charge a much more profitable exchange rate.  As such, the poor waiter or clerk has no clue what to tell you when you recognize the charge in US dollars is not accurate.  In Spain and Portugal we have not run across that practice.  It seems to be prevalent in Italy.  


@robdhubb, We very much appreciate your sharing your experience and knowledge in this forum. It can be tricky using cards overseas.  Great information! Thank you so much for the post. ~ Suzy