dont let vince fool you..sydney is EXPENSIVE...even the OS tourists say that....the beaches are little coves spread apart and crowded as heck and the water in the past has been unswimmable due to the efluent in it. sydney has major problems with ethnic gangs and is the gay capital of australia. car parking in the city will cost you $50-$75/hour.
now Australia has 2 spots that are a must see...perth and adelaide. pristine waters, literally 100s of km of unbroken white sand with the occassional person on them,...affordable and large enough to have everything...
I fail to see what's a must see in Adelaide. Since they lost the grand prix to Albert Park, there's nothing significant attracting overseas visitors. Don't get me wrong, it's a beautiful city and very close knit and family orientated, half my family live there.
After backpacking around most of Oz, my picks for must see places and beaches are;
Mission beach
Airlie beach for backpacker mayhem
Cable Beach in Broome
Kakadu
Margaret river just south of Perth
Kings canyon and..
Billy's Beach house on the Gold Coast