If you're doing a OW award, you aren't limited to transatlantic segments on AA, in fact you may be better off using a OW partner to help satisfy the 2-additional partners requirements. That opens up some more routes:

YYZ-LHR (BA)
YUL-LHR (BA)
YVR-LHR (BA)
MEX-LHR (BA)

Hmmm...come to think of it, that may be all.

IB only flies MAD-JFK/ORD/MIA
EI only flies DUB/SNN-JFK/LAX/ORD?
AY only flies HEL-JFK

Kind of pathetic compared to *A I think.