I have an Admirals Club annual membership already (and in fact am currently in the ATX AC as I type this response), but after spoiling her with access to LHR's Flagship Lounge in Feb (DFW's is nothing to brag about of course, at least not until the remodel is completed next year), I was hoping we might have access to one again in LAX, but alas, unless AA changes its policy (I did fire off an email; not overly-optimistic that they'll be receptive), we'll just have to slum it in the regular Admirals Club non-special section like most everyone else, lol.
Just for future reference, if you are flying AA to the US from LHR, and you are an EXP, you do have other, even better lounges (in most folks opinion anyway), than the AA FS Lounge. You qualify for the CX F, BA F and Qantas lounges as well in LHR T3.