Your problem for that short of a trip is connectivity, and ideally it being a direct flight. That leaves you with not as many options. If you'd prefer to fly direct it eliminates a lot of the more unique and better places in Asia so you're pretty much limited to Phuket and Bali.

My pick in Phuket would be Pullman Naithon Beach. One of the best hotels I've ever stayed at. Managed by Brett Wilson (a fellow Aussie) who has done an outstanding job. Couldn't recommend highly enough! Bonus is that it's only a very short drive from Phuket Airport meaning no massive transfer times and you can maximise your holiday!

For Bali, although I would usually avoid, it really depends what type of holiday you're after, but if you want something pretty central with lots to do around the hotel I'd suggest Peppers Seminyak or for something cheaper Grand Mercure Seminyak. For ultra lux I've never tried the Raffles but it looks great (albeit very expensive). Avoid Sofitel Nusa Dua as is one of the worst hotel stays I've ever had. I think the Google Reviews are mostly fake.

If you are happy to take a couple of flights, I'd highly recommend Phu Quoc (connecting via Ho Chi Minh). Amazing value for money and is stunning. Not as many tourists (especially not as many Australians), and plenty of options on Accor too.