I think I've visited many of Australia's popular tourist spots, but I am still very keen to properly explore the West Coast.
I think what really distinguishes Australia from much of the world is the uniqueness of its nature. The landscapes you find in Australia generally cannot be found elsewhere in the world. I particularly love the Outback and Top End – where everything stereotypical about Australia merges into one –red sand, intense heat, rock formations, animals, birds, bugs, stars, outback pubs and some of the only opportunities for visitors to access and learn about Indigenous culture. Right before moving to Hong Kong I did a road trip from Uluru to Alice Springs, via Kings Canyon and the West Macdonnel Ranges. The magic really hits you once your phone coverage stops and you're driving on an unpaved red earth road, with nothing but sand and the occasional kangaroo.
In terms of hidden gems, I really like the Grampians National Park, which is around 3 hours northwest of Melbourne. I always recommend visitors to go here as I think its probably the closest thing to an 'Australian safari' with the highest density of animals that I've ever seen in Australia. The whole area is swarming in kangaroos, wallabies, emus, echidna, lizards and if you're lucky – the occasional koala or platypus. I did a camping trip out there a few years ago and every morning we woke up completely surrounded by perhaps 20 kangaroos snooping for food. As soon as we would come out, they would all start hopping away.