If you're willing to pay BA surcharges on an award for the outbound, for just a bit more you can book a one-way on TAP Air Portugal in business from BCN/MAD to the US with cash.

To BOS - $989 - https://www.google.com/travel/flight...4AVDA3JkD3vnw5
To NYC - $1047 - https://www.google.com/travel/flight...9EgxA6SuJn3h58
To DC - $1102 - https://www.google.com/travel/flight...RQD3e6f9JLPkX7
To YTO - $968 - https://www.google.com/travel/flight...AnjfK2UpBPXeX9