When you travel it is often either very convenient, or even possibly necessary, to have some local currency. From tiny purchases to remote little shops that don’t have a credit card machine, you just need real money vs plastic. Last summer, for example, my wife and I took a week holiday in England and had a blast visiting a flee market and found lots of bargains – cash only.
But there are countries where cash is almost pointless. Sweden, for example, could become a cashless society one day and maybe sooner than we think. People there, just like here nowadays, pay for even super tiny purchases with a card and they all use chip-N-pin for the transactions. Simple, quick and easy.
But notice what is happening at the end of this month. Sweden is changing their bills and old bills will no longer be valid for spending (you can, for a fee and some real effort, still exchange bills past the expiration date).
And while this year it is paper money, next year it is coins as well (well most of them anyway).
The point is if you are thinking about returning to some country down the road you may decide it is not worth the exchange fee of a few dollars to change your remaining local currency back over to US dollars. But here is an example where doing this could cost you.
Beyond that it is always smarter if you can to pay with a travel card to earn points. Sure you should try to use a travel card that does not charge an international transaction fee but I have shown in the past, depending on currency fluctuations and the cost of the transaction, this fee can be all but be a myth in reality. But also keep in mind many airport exchanges locations, if you go back to the same company who you started with, will allow you to change back what you have left over at no extra fee (other than your first fee). – René