Go to Adelaide it is very relaxing no real hustle and bustle. Some nice beaches down there. Very flat no good for surfing
Don't bother with Melbourne.
If he goes to Sydney. Stay in Sydney and don't venture to the suburbs. Its not worth it. If you get to Redfern you have gone too far. Sydney City, The Rocks, Sydney Harbour, Manly and Darling Harbour are the only places worth seeing.
Canberra.
Its good if you are a political analyst or something
If he comes to the Gold Coast, don't bother with Surfers Paradise by night. We have the best beaches in the world and have alot to do by day like theme parks and wineries, sporting events the list goes on.
Byron Bay is a must see place and is great to see the alternate laid back lifestyle.
Great Barrier Reef, Hamilton Island and the Whitsundays are awesome.
The top end is ruggedly beautiful Darwin the Kimberlies, Alice Springs is well worth a look.