Hi Yellow Rocket
I'm not with QF (one day I'll get there though
) but I'm quite sure the broadest range of flights will be out of Syd base and then probably Melb base.
Someone from QF will be able to confirm the trip patterns. In the meantime, if you go onto the QF website and click onto their route map it will give you a rough idea of where they fly to out of Perth.
Hope this helps
Cheers
vdd