I've used my LATAM number on aa.com after the reservation is ticketed and I get MCE seats for free. I got a plastic card for this year and I've only had to use my plastic card twice in the last year and a half to get into a lounge, both times at the LAX T-4 AC when their reader wasn't reading the BPs. I've also got free food and beer in flight about 75% of the time since the AA system just shows OWE and doesn't break out the EXPs from the rest of us. Last time I had a lounge access issue was a couple of years back with BA in LHR that took a supervisor to read the rules and realize that LAN really was OW and that a Comdoro was OWE and allowed into the Flounge (not the CCR)!