There is an issue with WT+ with Australian/NZ originations is the AUD450/900 surcharge for WT+ rather than the normal USD300/450 elsewhere. Doing WT+ to LHR plus LHR-DXB-LHR will add AUD1800 to the cost, bringing the base fare from AUD2959 to AUD4759 ;

For status, you might like to consider an AA Platinum lack of challenge; easily completed on an ATW trip and would give you OW Sapphire status ( c.f. QF Gold ) rather than aiming for QF Silver. Travelling Westbound, if you were to travel WT+ to London, you would attain AA Platinum at London; travelling eastbound, taking the AA flight number to LAX and then AA to JFK you would complete it at JFK. ( if not stopping over in LAX, book on the AA flight number from SYD-JFK as a single segment and get the platinum bonus on the whole 9950 miles )

Dave