I will be in Australia for 20 days in November. I realize that isn't nearly enough time, but am looking to visit the following cities: Melbourne (arrival/departure city), Sydney, Brisbane, Cairns, and Uluru. Should I take internal flights? Or a combination of flights and trains? I would appreciate hearing from fellow travelers who have experience in taking both modes of transportation. I want to be able to maximize my time (this is my first visit to Australia) and be cost-effective. Thanks for your help!