Australia is a not very cycle friendly country, the "land of the tall white petrolhead." (AKA "the bogan.") That said, we have a very good, cutely diverse cycle community here. Advocacy is in a bit of a "brown age" in my opinion, especially compared to the 1990s when I was active, but a lot of that back then was our compulsory helmet laws (even off road on public land!) However, it's not as bad as all that, either. Melbourne has widespread infrastructure, most of it a few decades old and showing it, but maintenance of it is undertaken and the "Big Build" upgrade of our urban rail network is also resulting in some amazing off and on road paths and lanes.
One thing about Melbourne, now with 15 years exploring my chosen home, is despite the breadth of established infrastructure, a hundred years of urban sprawl into satellite rural towns has made backstreet routes preferable, in my opinion, to side laned main roads and, in most cases, only a few hundred metres in every 10km longer. 10% longer at worst. Realising this fact has got me "rejizzed" for riding lately and I'm in preproduction for a little, independent toob channel on the topic.
My pick for Australia's top bicycle cities if you're ever travelling here...
1. Perth Western Australia - very committed to human urbanism. Australia's answer to the south of France, well, almost
2. Canberra Australian Capital Territory - infrastructure is aging a bit but some fabulous backpacking out in the countryside.
3. Adelaide South Australia - the Australian home of urban renewal. Great winery tours, The Tour Downunder for race fans and the Mawson Track
4. Melbourne Victoria - Goldfields for bikepacking, Gippsland Basin for traditional cycle touring.
5. Darwin Northern Territory but it's so damned hot, people literally just go out nude some days.
6. Hobart Tasmania, but get the hell out of town. The countryside is Tasmania's draw and what made a cycle tourist out of me growing up there
Brisbane Queensland has a good cycle culture but lousy urban "planning"
Sydney has worse cops (when it come to cycling, at least) than Melbourne and is a motor trafic hell hole mostly. Blue Mountains though! Beautiful!
If you want adventure and long rides in the outback, anywhere is good, although dangerous. More due to water and food sources than critters. Australians tend to tell fibs about drop bears (don't exist) and frankly, every continent has dangerous species. I'd rather take on spiders and box jellyfish than coyotes, cougars, bears and the NRA