At SAN, SJC, PDX, SEA Plats can definitely use the F line. At SEA and PDX there is signage to that effect. At SAN and SJC IIRC there is no signage, but they definitely let Plats through.

IME you do not need to be flying AA to use your plat card to get in through the F line; the ID checkers are not up on which airlines are partners with which.

GLD cannot at SEA - signage clearly limits to Plat/EXP. I'm pretty sure I remember being allowed to use the F line at SAN & SJC as a GLD, but that was several years ago. Can't remember what the signs say at PDX.