Decide where you want to go and research it - obviously wherever your son is is covered but Aussie is huge and you need to be selective. I spent three months there and only scratched the surface, Perth, Snowy Mountains, Sydney, drove the eastern coast road to Cairns, learnt to scuba dive on the GBR, abseiled and rode camels! Really, do some homework - it really is a very big place! ps - have fun