As a few have already said, the Gold Coast in Queensland is the best option you could look at ... unless you are pasty skinned red headed freckled irish folk, in which case you'll possibly go home burnt to a crisp with a few melanona's LOL
What kind of stuff are you into? If you like the outdoors or horse riding or golf etc would make a difference to where you stayed. There's some amazing places in country australia but I don't know that you'd get enough variety to stay in any one town for long.
Or do you want to wake up & surf then get drunk at the local surf club before heading out to surf again then hit the strip clubs in the evening? That's the Gold Coast ;-) But its also close to mountains with rainforests & walking tracks, some wineries, amazing scenery, its own airport, heaps of tourists, hot chicks in bikinis etc.
This is a typical sunrise view & apartments on the water like this are available from around $500 per week.
the skyline from a suburb 15 drive minutes up the beach from the city Surfers Paradise
You'll usually see dolphins every few weeks & if you are there at the right time can get pretty close ...
But there's beautiful places all around this country so it all just depends on what you like!