Maybe head out to Alice Springs area then, there's plenty of stuff to explore out that way. Incorporate things like Oodnadatta Track, Lake Eyre,, Lamberts Centre of Australia, Boggy Hole, Chambers Pillar, Kings Canyon, The Rock, etc etc
Or head North up to Lawn Hill, see Blacktown Tablelands on the way up and eventually loop back to the East Coast visiting places like Cobbold Gorge, Finch Hatton Gorge etc etc along the way.