Australia over the last 1Ĺ years, has generally been the wettest since 1974-1975. So I would suggest you do some research regarding places you may think of going to, to ensure they are not underwater still.
You could go to Cape York to the Tip, August is usually the best time to get there as the rivers are down and vehicles can get through, however that would mean an organised tour, which wouldnít be cheapish, but would probably get you to places and things you have never heard of.
My first successful trip to the tip was in 1980, third attempt. Water was down to waist high; we floated the bikes across the Jardine River.
The Great Ocean road is quite over rated, yes itís not too bad, but I wouldnít call it spectacular at all. I have been on it on motorcycles for the last 45 years, but now itís just a tourist thing with overblown suggestions.
Central Australia, whilst often freezing in the nights at that time of the year, can be terrific. Bring a tripod for astro photography. One favourite pastime is lying down wrapped in a sleeping bag and looking up into the night sky and counting satellites.
My suggestion is to contemplate central Australia; itís the time I have often been there. Bring warm clothing and sunscreen.
Another suggestion may be the top end either in the Territory or the top left corner of Western Australia. This is getting sort of near to the end of the dry season and the water holes are starting to dry up, meaning the wildlife starts to congregate. Best would be a tour. Iíll try and get some information from a Canadian lass who stayed at our place for a while, she and her significant other had a whale of a time on a trip up the top end. Both from an Aboriginal cultural and food and custom thing, as well as general sight seeing. Sheís quite into photography as well, stunning piccies.
The east coast of Oz is reasonably touristy, nice in tiny bites, thatís all.
The Flinders Ranges in South Australia is or could be very good at that time if the spring comes early. Air trips over Wilpena Pound and some organised trips to some of the spectacular lookouts and gorges are good. Four days to one week there, should see many things, but on the other hand you could find somewhere nice to just travel out from and come back every day.
Mt Augustus in Western Australia is huge, itís the biggest rock around, makes the rock in Central Australia look like a pebble.
Lots of things to do, just requires money and time!