The general rule is: the more affluent the country, the better off you're with paying with CC. The cost of exchanging paper money is proportional to the prices

The general rule is: the more affluent the country, the better off you're with paying with CC. The cost of exchanging paper money is proportional to the prices of other things in the country. Especially in big touristy cities in affluent countries like France, you can easily lose 10%+ on currency exchange. So in EU, stick to CC, and maybe just have 50 bucks of emergency cash. On the other hand, in cheap countries like say Georgia, Kyrgyzstan, exchanging paper currency (especially USD) to a local currency and back to USD is almost free (<~1%)