I just booked a flight to the states, Miami to be precise. Qantas is pretty much the only choice for a MEL-LAX-MIA direct. Delta/Virgin and United both have an additional stop in the states, and the timing is usually pretty bad.
Anyways, while looking for this flight, I found that using the multi-city option on the Qantas site had the best deals. Perhaps not deals as such, the price of the flight is still about the same at 2k, but I got a day to bludge around in Sydney and 3 in Auckland. Before going off to the states. But the flight back is a direct MIA-LAX-MEL.
So I guess the moral of the story is that if you are flexible and travelling Qantas, try the multi-city option, and see where else you could stop off at.