I would suggest contacting AA in the US first. With the removal of GST you will likely find that the fare works out cheaper. Also, since they will bill you in USD you will not be stung for a AUD-USD conversion fee. I often have used AA in US/UK to book QF domestic tickets since it is often cheaper.

Don't bother with the AA web site, it is dire at selecting cheap booking classes for QF.

When checking, remember that the order of fares cheapest -> most expensive are

O(*),N,S,V,L,R,M,K,W,H,Y,J

* O fares are the only ones not bookable other than on QF website

Dave