Start crediting to BA Executive Club if you're already flying premium cabin.

Flagship Check-In now applies for OW Emeralds so you'd get that plus Flagship Lounge access on all AA flights. Once you reach BA Gold Guest List* you are recognised by AA the same as Concierge Key members and so quite often get the CK treatment (Cadillacs to the aircraft etc.). The only thing that you'd need to achieve would be you'd need to take 4 BA flights to be eligible for Sapphire/Emerald status.
https://www.flyertalk.com/forum/brit...rd-ba-ggl.html


*Earned by hitting 5000 tier points which equates to:
-125 AA FC segments of less than 2000 miles
or
-36 AA FC/premium transcon business class segments of more than 2000 miles
or
-24 longhaul/premium transcon FC flights
The renewal for GGL is 3000 tier points plus 4 BA segments per year, so easily achievable on your flying pattern.