Well, normally I would have considered a plane (and I do realize that air travel is often cheaper), but I have two factors pushing me to look at trains:

1. We likely won't be covering these same legs by car (we're picking up a car in Cairns and dropping it off somewhere in South Australia (not sure exactly yet--we're borrowing it from a friend), and we want to see any scenery (or even just the lay of the land--the whole point of this two-month trip is to really get a feel for Australia, and that can be done much better on the ground than in the air), and

2. I'm a bit of a railfan, and while I'm also an aviation nerd, too, I really like taking trains over planes.

We may end up looking at either the Indian Pacific or the Ghan (or both), too (hey, I said I was a railfan, and those are two of the world's greatest journeys!), but those get pretty pricey (unless I can get one or both of those discounts!).

Thanks for all the help!