I asked Amex email customer support about AA's participation in the program, and received the following written (email) response. Anyone want to confirm that this is accurate? It's awfully strongly worded, and quite unambiguous to my eye...
Dear Edelman:
Receive a complimentary companion ticket with the purchase
of a full fare, first or business class or Concorde ticket,
depending on participating carrier, when the purchase of
the original ticket is made through Platinum Travel
Service. Offer applies toward the purchase of International
Flights only.
American Airlines's participation is not limited only to
the Caribbean. You will have access to its entire
international route network, subject to the other
constraints of the program. If you have additional
questions, please feel free to e-mail us again.
Sincerely,
T. Joseph
E-mail Servicing Team
American Express Interactive Services