Originally Posted by Steve M

Also, consider applying as much as you can to your final hotel bill. Often, this will consume all of your remaining local currency, and then you've used its value without having to convert it at all. It's easy to do this - just apply your excess cash to your folio at the front desk, and then they'll charge the remainder to the credit card on file upon checkout. This is assuming that you have a post-pay reservation. Note that even if you have a no-foreign-transaction-fee credit card, this method still saves you money, as you end up paying nothing to convert your spare cash back into USD.