If you had to pick three areas to visit in Australia, giving each ~a week, which would you pick?

Right now I'm thinking Perth, Alice Springs, and somewhere from where I can easily get to the Great Barrier Reef.

I've been to Sydney and Cairns, and much as I want to go back to them both (very much), I'd like to do new areas first.

What areas would you pick? Same as I've picked? Or different? One of the islands - Kangaroo Island, Tasmania, other? Somewhere in the north part of the Northern Territory?

You would have to tell us when you were thinking of doing this because weather has a great bearing on what and where to go.

Kangaroo Island - which some (not all) think over-rated - only as a side trip should you decide to make Adelaide one of your bases. Tasmania and Darwin-Arnhem Land are attractive destinations but don't work very well in combination if you consider the weather.

Thanks for the replies! Ivenotbeeneverywhere - my schedule is completely open. I sort of have September in mind, but could go at a different time if it were better.

Maybe the weather is such that getting good weather in those three places at the same time of year is unlikely? Hmm.

Depends not only on the weather but also your interests. September-October should be a great time in general, early spring. Not too hot yet in the north and in the interior, starting to warm up in the south. On the east coast, you should have beach weather anywhere north from Coffs Harbour, roughly.

Cairns/North Queensland for sure, since you want to see the Barrier Reef. The Red Center (Uluru, Kings Canyon, Alice, etc) should also be fine then. Question is what the third area would be. An number of choices, besides Perth

-Tasmania? Could still be a bit cold then. But a wonderful place nonetheless.
Southeast Queensland? - a perfect time of year here. A beautiful area: Lamington National Park, Fraser Island, Noosa, etc
-The Top End (Darwin, Kakadu, Litchfield)? - it will be hot, but a great place to go for wildlife, and adventurous stuff
- Adelaide and environs? - it will be lovely there in spring. Much more to see than Kangaroo Island, like the wine valleys and the Flinders ranges ( a taste of the Outback)
-Melbourne? - consider a drive from Adelaide to Melbourne along the Great Ocean Rd over 3-4 days, with possible side trip to the Grampian Ranges. Very nice.
-Sydney and environs? It should be pretty nice in Sept. Lots to see in and around the city, which is among the most beautiful in the world. Maybe include an overnight trip to Canberra.
-The Kimberley region, WA? Getting hot, but an amazing part of Australia to visit, especially for the more adventurous. The remote Bungle Bungles are the most spectacular natural rock formation in Australia, in my opinion

Well that would be the best time to come actually because everywhere will be good. Tasmania is wonderful at that time of year and although it may not be swimming weather it will be beautiful after the rains of winter ( we hope) and besides there is so much to do and see that weather hardly comes into the equasion as its never too cold and never too hot.
Its a bit early for the wildflowers in Perth unfortunately as that is rather special. The only unfortunate thing is the cost of getting to Western Australia from the east coast - always expensive as they have a captive customer group but you can sometimes get specials. I would avoid travelling on Tiger Airways though should they go anywhere you maybe thinking of going as they have a dreadful reputation i.e. one flight attendant got sick and the whole planeload of passengers were left sitting for 3 days in Tasmania.
So mainly it is up to you where you want to go and what you want to see depending on your interests.

I am putting this on another post so may as well put it on here too - for Tasmania information on just about everything.

http://www.discovertasmania.com/brochures

Come back for specific questions that you may have and we can answer them - hopefully

September is an ideal time to visit Perth! The Kings Park Wildflower Festival runs from Sept 1-30 and the flowers are a sight to behold. It's also a good time to visit weather-wise.

We spent two weeks in South Australia last September - we found it a good time to visit - ideal hiking weather for us.

There's so much to see and do in SA - we never made it to KI but we didn't feel that we particularly missed out.

Loads to do in WA too - that week will fly by.

Thank you all! Great information, great link. I need to keep reminding myself not to try to do it all in the time I'm there -there's far too much to see and do; I'll just need to plan to go again.

Good to know about Tiger Airways. Perth really is, as you said, a captive audience, isn't it? Well, I'd like to go sometime, so I'll see if I can find a good deal. If not, I'll add it to the "next time" bucket.

Ralph, so many great ideas - I think I need to ponder those! Half the fun is planning the trip. You've all given me some great fodder for daydreaming. Thanks!