Make take:
Cancel the AmEx Plat card and get the Barclay Silver and;/or Citi Exec.
AmEx has up'ed the fee to $700. The MIA Centurion Lounge is always crowded and they serve cheap food - noodle dishes and chicken thighs.

Living in MIA - AA overwhelming dominates.
Based on spend you will get AA EXP, and will get upgrade opportunity on your flights.

Things change when you move.

I will likely cancel my AmEx Plat when I get a $700 renewal bill. I don't use most of the travel benefits from them. And to get some of the money back - you have to do lots of coupon transactions.

The Barclay Silver gives 3X on AA flight purchases. You might have to start with the Barclay Red, then later upgrade to Silver.
Citi Exec card gives you AA club access.
Maybe get the CitiExec to start. Since you get lounge access.