One of the best places in Australia to go for a scenic road trip is South Australia. It is known for being the city of churches, but there is so much more to the city than the churches alone.
You can easily find a campervan or motorhome hiring depot and choose to do a round-trip, or one-way trip to Melbourne or Perth.
It might be possible to do a one-way trip to Alice Springs, but you will need to check with the hiring company.