Because we stay on the French side , we usually pay in Euros because although everyone accepts dollars it's with at least a 10% exchange rate. We get Euros at the ATM and use our Capital One bank card because they exchange at current rate and no fees.
I always use a CC on the French side unless the establishment gives 1 to1 cash. If they don't take a CC or give a decent exchange rate for US dollars I don' go there.