Time pressure, combined with the vastness of the Australian continent, may lead you to consider taking to the skies at some point in your trip. Australia has a few low-cost carriers, but deals on the main airlines often compete on value when you add baggage (and reliability).
Australia's main domestic airlines service the large centres with regular flights. The major players:
A number of regional airlines operate within smaller geographical parameters and fly into regional airports.
For the highly organised, Qantas has a Qantas Explorer (www.qantas.com/us/en/book-a-trip/flights/qantas-explorer.html) deal where you link up to 30 domestic Australian destinations for less than you'd pay if you booked flights individually, though you must book them together.