Oh yeah, if you're spending a holiday in Aus you sure as hell don't want to drive anywhere. You'll waste way too much time. If you book far enough ahead cheap airline flights are comparable to what you'll pay in fuel anyway.
Random list of things to see in Australia off the top of my head:
The DaintreeKakaduLake EyreGreat Barrier ReefThat's if your into out-doorsy stuff though and the issue is that most of that stuff is a fair hike from any decent cities. If you want to hang out in another city then you'll want to go to Sydney or Melbourne, I like Melbourne more myself (they have fairy penguins and cooler night life) but you're probably going to want to get a tourist shot with the opera house and so that would mean Sydney. The weather and the beaches are better there anyway. Also, it's cheesy as hell and I haven't seen it since I was a kid but I can confirm that Uluru at sunset or sunrise is just fuck*ng magical.
End tourism department pimping.