MarkP24
Enjoyed the stay although I found the Balcony room to be somewhat small, particularly on the top floor which has a lower ceiling than the rest.
They are doing a breakfast buffet but guests must wear a mask (understandably) while using.
The staff were pleasant and helpful.

The hotel arranged to have the doctor visit daily, each morning. He came to our room slightly after 9AM and we were done in about 10min, documentation in hand.
The option is for either PCR or Rapid Antigen. Since the US will accept either if test is within 72 hours of travel, we chose the faster and cheaper Antigen test which was €20 per person, paid directly to the doctor. I don't think you can beat that.

Here's info from the US Embassy including a link to places in Barcelona that are offering testing. I went through the list before finding out the hotel offered testing and it was no contest. If you're considering other hotels, it might be worth reaching out to them to see if they are offering a testing service similar to Cotton House.