Before someone says that this topic has been discussed berfore, please read it carefully. I think it may be a different idea.
According to
http://www.oneworld.com/ow/ffp/oneworld-status:
Sapphire status gives access (with one guest) to all Business Class/Frequent Flyer lounges regardless of the class of travel.
This means that a EXP/PLT should have free access to any OneWorld lounge. Of course, AA limits access to international travelers, so you might think that a EXP/PLT card will
not give you access to the AC.
But in Los Angeles, the AC is also the Qantas club. And Qantas
does allow club access for Emerald/Sapphire holders. So I believe that PLT/EXP holders should have free access to the Los Angeles AC for themselves and one guest.
The Los Angeles AC has a Qantas rep at the upstairs desk. I suppose you would have to check in with him/her. But you should have access. Also, to any other ACs that are also clubs for other OW airlines.