Griffo has nailed a lot of the important stuff. However, in mentioning Caiguna... a compulsory viewing is the Great Australian Bight cliffs, at lower levels, from Caiguna Eastwards.
Also... be aware of hot, strong, Easterly/N-Easterly winds at ground level, all the way across the Nullarbor, at the time of year you've indicated. Once a strong mid-Summer, high pressure system sets up in the Bight, look out.
He's also right about the Caiguna Roadhouse food. Best steakburgers and chips you'll find anywhere across the Long Paddock.
Flying the Outback Blog Archive Pilbara Air Safari May 2009