Actually, if you have a lot of AA miles, you could use them directly to get two OW award tix which combine CX and QF, e.g. SYD-HKG-LAX (the 1st segment on QF and the second on CX). A bit longer than a SYD-LAX N/S, but it might be easier to find availability for the dates you want, and it will be considerably cheaper in taxes and surcharges. That way you won't need to exchange your AA miles for QF points, which may not be that easy. You should be able to get C awards for 80K AA each (SYD-LAX N/S distance being less than 9K miles).