I took an impromptu trip to Australia because my friend wanted to visit New Zealand and Australia while he had a chance. I couldn't make the New Zealand portion, but we spent a week down under visiting Sydney, The Great Barrier Reef, and Brisbane.
I booked all of my lodging using Bookings.com, which worked out pretty well. The hotel in Sydney was in a great location, but a little run down. The serviced apartment in Brisbane was amazing, and cheaper than Sydney.
One of the highlights of visiting Sydney was a day trip to the Blue Mountains. We rented a car. It's about 1:45 hours away and a pretty easy drive. Even though I'm not used to driving on the left, it didn't take long to adjust.
The mountains are amazing, lush and green. As an added surprise, there are wild parrots living there, which was extraordinary.