Well as an Australian that has been to every state, and has lived in 5 different states, I can say avoid the east coast, lol
A few good non-mainstream things to see:
Litchfield National Park...like Kakadu, but less tourists, less crocodiles and you dont need a 4 wheel drive to see the major attractions. Less crocodiles also means its a lot safer to swim
The bungle bungles in northwest Western Australia
www.kimberleyaustralia.com...
Margaret River wine region (less people than the Barossa Valley in South Australia)
www.margaretriver.com...
Daintree Rainforest..watch out for Cassowary's
www.daintreerainforest.com...
There's plenty more too....so many I cant list them all. The best places are away from the more populated east coast, so avoid the big cities like Sydney, Melbourne and Brisbane if you want a REAL Australian holiday
Also, IMO, the Northern Territory, Far north and east Queensland and Western Australia are the most beautiful and impressive parts of our country....













