Originally Posted by
JAX2BOS
AA operates out of 8/9 which really isn't convenient unless you have a massive connection time between the carriers. It involves a long, annoying ride with the AirTrain.
The AirTrain ride is only 2 stops from 5/6 to 8/9 (or now, just T8 as AA has re-branded the full new terminal). However, the AA clubs are behind security in 8, so the OP wouldn't be able to access them without a boarding pass for a T8 flight, AFAIK.
BA operates from T7. I presume they have a lounge, but don't know if it is before or after security.