I think a lot of making the most of a trip is to realise your limitations (of time) and to make the most of what you have. I'm coming towards the end of a 6 week trip here and I now realise you need MORE TIME, although I did have 10 days in Perth (which I thought was a great place).
So far my time in Sydney has concentrated on the rugby, I'll do some sight seeing in the next week or so, but I did the drive up to Brisbane and IMHO it shouldn't be tried in one go. It's a good 10 hours NON STOP so if you add in brekkie/lunch/dinner (2 out of three)and a few loo stops it's going to take more than 12 hours. Much of the road goes through small towns and the speed limit is just 60 kmph , driving at night should be avoided as you get a lot of trucks on the roads and in truck vs car there is only one winner. I broke the journey for 3 days on the way up at Coff's Harbour which is about half way. I stayed at a great B+B , but they prefer not to have kids staying but there are LOADS of choices in Coff's. It has a wonderful beach and some nice restaurants. One of my friends recommended Port Mcquarie (sp?) as an alternate stop but as I just "overnighted" on the way back I chose Coff's again. We did a breakfast stop just outside Port Mcquarie and found a spectacular view at a wonderful bakery/cafe overlooking the river/marina.
I liked Brisbane and thought it was a well laid out city with lots to do. There are 3 or 4 themeparks within an hours drive as well as great beaches and Steve Irwin's (the crocodile hunter) Zoo Australia is an hours drive north. I thought they have a great concept, have planned and laid out the "attractions" very well. Very much worth the trip.
I also drove up to Bundaberg to do a scuba dive course, this is about 5 hours north of Brisbane and again with the road it's about as far as I would recommend in one go. To be honest not much to Bundaberg, but you can take boat trips out to the southernmost part of the barrier reef, if I had more time I would have visited Fras(i)er Island that I'm reliably told is a "must do" and spectacular place to visit. I think the drive to Fraser Island is about 3 hours from Brisbane. If you're going to go all the way to Cairns I think flying would be a better option as it is another HUGE drive. I like driving on vaca , particularly in the US, but the interstates in Australia are no where near as well maintained and presented as those in the US. Much of "highway 1" is two way road with passing lanes every few miles, no lights, a lot of animals get on the roads at night and it's the most dangerous stretch of highway in Ozzie. I liked the drive in the day, coz there is a lot of nice scenery, I didn't like the small amount of night driving I did and would strongly recommend avoiding it if possible.
With so much else to see I think you might find the Ayre's rock a trip too far unless you add more time but I do understand why many people think of it as a "must do" as I said it's a question of realising your limitations and prioritising. I used my friends who live here for most of the info prior to my trip, but there are also a number of sites I looked at to get info on other places ( Philip Island south of Melbourne being one). I'll try to dig out the websites when I get home in January