Translation of sadness in Spanish

We drove to the hotel Rex where we made reservations in advance. However, once there, two American guys told us that they had a voucher from a travel agent and the price was like half of it.
I understand that you use the article 'die' when talking about a feminine object, das when the subject is neutral, and der when talking about a masculine object. But how can you remember all these?
This moment by itself made the flight and its delay worth. Although we regarded Arequipa as a hub on the way to Chile, it turned out to be a very charming city.