I am on the west australian coast, (though Danish) and have been to the east coast a few times, both Sydney, Melbourne and Brisbane.
This is one huge country/island and there are plenty of places to photograph, , but everything is so far apart, that it is almost impossible to cover everything, unless you are Rubert Murduch with a bottomless wallet.
In WA, there is the South West (3-4 hours drive from Perth), which is beautiful, better in the short time of spring or autumn, I think each season here is about two weeks each ;-)
then there is the far north, which is rough country, with gorges, lots of wildlife, the Kimberley and the also the Bungle Bungle is an interesting area, that i personally would like to go and photograph one day. its only 2-2500 km north of perth :-)
Damn there is so much to see here, it would take a life time, its an amazing place.
Now, don't forget fly spray, plenty of sun lotion, cos it gets hot here. conditions here can get very extreeme.
If you are planning on going to the Great Coast Road south of Melbourne, don't take a tour, drive yourself so you can photograph when the light is right. I did the mistake myself, though it is a 3 hour drive from Melb.
anyway, I hope you have a fab time when you get here
Henrik
A Dane Down Under