Australia - Sydney, Cairns, and Ayers rock / northern territory - suggestions?

So I took a very similar trip to Australia 2 years ago, nothing was really planned outside of the opera house and reef.

Bondi beach was really cool, we did a lot of climbing around rocks and picture taking there, but the main attraction is the house in Sydney. I heard they completely renovated a lot of the Darling Harbor, so I'm sure that's really cool now, plus there are some aquariums and things around there. The tower there (can't remember name) is neat, you have a couple options of either going out and being strapped on, or just staying inside and snapping pictures. A famous church is near as well, my friend got us kicked out because he wouldn't stop taking pictures, but whether you get some or not, it's a neat place to see regardless.

Cairns was without a doubt the best part, we did the reef and some trip up into the hills for Koala bears and reptiles, so for me it would be like living near Venice, CA just better. There are a lot of friendly tourist pit stops that will help you plan things out, and they will also group things together for you for discounts and using their service. We just snorkled because you see everything as you do with diving, except it's safer and you have no restrictions on flying afterwards. Tons of cool shops and things to do, you won't want to leave I promise.

Melbourne for me sucked, I don't drink, and there's basically a Casino and lots of pubs to jump around to. We ended up renting a car and driving 2 hours out to some beaches and the wall which was awesome, but the city itself wasn't really my thing, however it's probably right up most peoples interest. We checked out the Dracula's Cabaret (no nudity) and it was a blast, it was honestly probably one of the funniest and well put together broadway type things I've ever been to. Then there is also the Penguin Parade as well, they only come out at night, so if that's an interest it's not a day time thing.

in sydney spend a day or two wandering around the domain, see the art gallery and botanic gardens and opera house, wander around the rocks (they have weekend markets) and grab a beer on the roof of the glenmore hotel (great views of the harbour).

if you want to burn some money do the bridge climb, it's very worth it. catch a ferry to manly and eat fish and chips and drink white wine on manly beach. take your swimmers, and bring your hat and sunscreen, it's summertime. we have no ozone layer so cover up or you'll get fried.

go to taronga zoo, its one of the best in the world (better than san diego i reckon and san diego was great).

rent a car and drive to echo point in the blue mountains, theres some easy hikes around there if that's your thing, grab some lunch in katoomba.

if you have more sydney time i love the south coast, i spend a lot of weekends driving down to kiama and going to the beach there and swing by the nan tien buddhist temple, its pretty cool.

up in cairns do the snorkelling / scuba diving thing, and go visit kuranda. its a lovely town up in the hills with a cable car ride to get there and back. apart from that just rent a car and drive up and down the coast, go check out the daintree rainforest (world heritage), but be careful of the ocean because its jellyfish season and those things will fucking kill you in an agonising way. welcome to australia. there are netted off beaches where its safe, so just ask the locals where to go if you want to swim. otherwise cairns is pretty boring outside the reef activities, eat lots of tropical fruit, drink lots of beer, rent a boat, do some fishing and unwind.

melbourne is a sjw shithole but good for the cafe and art scene. apart from that its pretty shit.

if you do have time down melbourne way i cannot recommend the great ocean road trip enough. rent a car and take a day or two checking out torquay and take the great ocean road to warnambool and then head back. i've taken a few girlfriends on that trip and they all raved about it.

we drive on the opposite side of the road to you guys, so just remember that wherever you are in the world, you as the driver are next to the centre line of the road. its how i stopped plowing headfirst into traffic when i was driving around the states.

the red centre is supposed to be amazing but i haven't been, and its summer so it will be fucking hot. like 45C hot (113F). also bear in mind driving around this country is huge. it took me 5 days non stop to drive from perth to sydney. its about 10 hours sydney to melbourne. 13 hours sydney to brisbane. your adelaide to alice springs will be about 20 hours on the road. check with the rental company you may be able to rent a car in sydney then drop it at a depot elsewhere. this isn't europe, so don't think you can bounce between cities with no hassle, its a big trip to get anywhere from anywhere.

if you're heading up to darwin then you'll be wanting to check out kakadu. there's tours in the wetlands and you can check out the 15 foot saltwater crocs doing dinosaur things (long period of nothing, then a burst of nom nom terror)

any questions i may be able to help out with info. our dollar has just taken a dump against the $US so you're coming at a good time.