Originally Posted by
spainflyer
Now, if I want to pay in pesos, at the end of my stay in Buenos Aires (not pre-pay), does that USD price translate at the official, Banco de la Nación rate?
YES
Originally Posted by
spainflyer
do I have to pay with a credit card which will be charged in USD?
You can pay in pesos or dollars. The choice is yours. The rate the hotel uses to switch between the two currencies will be the official one.
If you choose to pay in pesos, it's no-one's business but your own how you acquired them: you are paying in pesos, not blue-pesos.