hi Andy B
This trip should be very good it takes you to very good places and you will see lots
In Sydney have you got any plans there a trip to the Blue Mountains if it is not cloudy is good and a Harbour tour on a ferry is also good to get the best veiw of the city go to the AMP Centre Point Tower in Market St it is not far from your hotel it is a tall tower in the city
The island and rain forest will be very good the road to O Reillys gest house you will wonder how they got it there but it is out of this world when you get there
The Australian zoo I hope Steve is there the day you go he is a wonder how game you can get.
Port Douglas a trip to the reef is a must see part of Australia if you can get back to Cains for a day go on the train trip to Kuranda and back down on the tree top chair lift do not go down on the train go up as the brakes squeel all the way down and it will drive you mad you should be able to get a trip from Port Douglas to there
If you can not do the train trip got to the Daintree National park
Alice Springes you will see the harsh dry center if you plain to climb the Rock at Uluru DO TAKE a BOTTLE water as it is the dryest time of your life climbing it the sunset or sun rise is a must see
I hope you enjoy Australia the trip you should be very good to do The Blue Mountains in Sydney you should be able to get day trips but if the weather is cloudy give it a miss if it is clear it is a must see.