The Northern Territory is a mecca when it comes to 4wd touring. Whether you stick to the main roads or hit the bush tracks there are endless options.
On a recent trip to the top end I had 4 passengers from Melbourne, They drove to Mildura in their car and left it in our garage. We traveled up the Stuart Highway doing all the major tourist attractions including Ayers Rock, The Olgas, Kakadu, Litchfield, Kathrine Gorge, Darwin across to Kunnurra then on to Broome.

From Broome we drove down he west coast to Port Hedland turning off to Newman then on to Mt Magnet. From Mt Magnet we went down to Kalgoorlie where we visited the Super pit and a few other attractions.
From Kalgoorlie we went to Wodinna Spending the night before the last leg home to Mildura. As well as visiting these places we also checked out the touristy things. This trip was fully accommodated and took 20 days. It would have been a bit better with a few more days but its all the time these lovely people had. If you want I can forward their number on to anyone wanting a reference as they have no internet.