In my opinion the only way to experience the vastness of Australia is by driving. There is one main highway on the continent: Highway 1, which is the longest national highway in the world. It circumnavigates the country, connecting all mainland capitals. If you've got time on your side and a car at your disposal, it is the ideal way to see most of the country.
Fortunately when I was in Australia last year, I had both. In order to complete my plans of circumnavigating Australia I had to do a lot of driving, including driving in some very remote parts. This is when it becomes fun for me. I don't like driving in crowded cities or on highways full of traffic, but I absolutely love road trips. I like not having a clue when or where you'll be sleeping at night, cooking simple food on stoves and watching sunsets. But most of all I like the freedom that comes with road trips, the ability to change your mind every second and to do whatever you want whenever you want. I'm addicted to it.