I realise that this may not have a direct connection with the opening poster, but reading the replies above bring back wonderful memories of my backpacking days, which included the Pacific Coast Highway from Cairns to Sydney. I was there from May to the start of July (when I flew across the Pacific to Los Angeles). Therefore It was their "Winter" at the time of the visit.
I loved Cairns, North Queensland, the gateway to the Great Barrier Reef. In Cairns as with all the stops I made, I stayed at a Backpackers Hostel. Also while staying at Cairns, I had the privilege to visit Port Douglas, about an hour's sail north along the coast, with the rainforest plunging right down to sea level. From Cairns I was able to snorkel over the corals of Green Island, the ideal spot for beginners, as I was at that time. From Port Douglas, I sailed on one of their smaller boats to Low Isles, where the beach slopes away more rapidly than at Green Island, therefore the coral growth was much more luxuriant.
I think this was the highlight of the whole vacation. Snorkeling and diving in that area is at its peak during their winter, as they suffer the monsoon season during November, I think, through to March or April.
Other stops I made included Townsvile (for Magnetic Island), Arlie Beach (for the Whitsundays - marvellous fringe reef corals at Heron Island!), Hervey Bay (for a day trip to Fraser Island, the worlds largest sandbank and home of the purest freshwater lake in the world - Lake McKenzie), Brisbane, and after crossing into New South Wales, Byron Bay, Coffs Harbour and Sydney, which included an overnight stop at Katoomba - the town that serves the Blue Mountains National Park.
I spent twelve days in Sydney before boarding the plane bound for Los Angeles. Sydney was okay, with a superb harbour, but the city itself looked remarkably like London, with even a central park named after the London counterpart - Hyde Park.
In all it was a FANTASTIC, unforgettable experience, especially after a five-day stop at Singapore on the flight from London (near where I live) to Cairns, and the 24 days in California, ten of these spent at a hostel in downtown San Diego, my fave American city.