the premium lounge at concourse E is pretty good for a US, nonflagship, lounge being shared with BA and AA (and others?).

The best part is self pour beverages, well of course!

AA F seats v good and the new Biz seats also v good, though I do prefer UD 747 with BA vs Biz on the new AA 777.

No idea about the upgrade chances tho - have had paid upgrades with BA before, but when asking an AA rep recently, he looked at me as tho I was mad.