AA awards are available on both BA CE and BA CW.

http://www.aa.com/apps/AAdvantage/Vi...lineawards&a=b

Of course, when I say "available" I mean 'available in principle". It requires advance planning and flexibility. It helps to join the BA Exec Club because you can then check award availability online (if award seats are available to BA members, AA can get them for you as well).

EDIT: Ah, now I understand the question. Indeed you can't get AA awards on BA transatlantic, but the world is a bit bigger than just transatlantic and intra-Europe.

Aadvantage has a few great deals on BA. LHR-India, for example, is only 60Kmi in CW. These flights are longer than ORD-LHR but the latter costs up to 60Kmi in coach.