DK and I are planning a trip to Australia for October - figured it's spring for them, so not ungodly hot there and we can celebrate our anniversary. We'll be flying my parents to TX to house/baby/dog-sit for us. They did this once before and offered to do it again (Plus, we cover flights and all costs beyond food and gas, they get a good couple of weeks with the grandkid, and they'll both be retired by then, so no worries about vacation time - it's a win for all.)
Right now we're looking at ~2 weeks or a bit more to account for travel, split between 3-4 locations.
Melbourne area ~> Tasmania ~> Sydney ~> Cairns (or a resort on the great barrier reef)
If you've visited any of these places and can provide feedback on things to do or avoid, and travel within Australia, I'd love your feedback. We'd rent a car in Tasmania (probably spend each night in a different location), and possibly for a day or so in Melbourne. (I want to see the fairy penguins on Phillip Island, and it's about a 2 hour drive - so we'd rent a car or book a tour company.)
We'd plan to fly between cities/locations, with the exception of Melbourne <-> Tasmania (depending on the order of the trip) - that would be an overnight cruise on the Spirit of Tasmania.
We're planning to get SCUBA certified before the trip because while we love to snorkel, I know we'll see more on a SCUBA trip to the reef.