Or you can donate them to your local UNICEF office when you get home. They run the change for good program.

Normally, we don't have much left. Whatever is, I put in an envelope and save till next time - it's either pounds or euros and we know we'll use them eventually. I do like the idea of using it to pay down the hotel bill. Thanks for sharing!

You're confusing inflation with commodity price increases.

I always pay down my hotel bill, or buy something at the airport and put remainder on the credit card. I've gotten good at estimating how much cash to withdraw from ATMs as well so that I'm not too heavy in local currency when leaving a country. Not much point in keeping currency as a souvenir as I take photos of all denominations of a currency in each country I visit.

There are certain currencies I know I will need again in the next few years (e.g. Europs, British pounds, Canadian dollars, CFA francs) so are no issue. For the others, let's just say I have things like CDs (and cassette tapes going back some years) and socks that were bought to use up small amounts of non-convertible currencies.