I'd swap Adelaide out for Tasmania inside. Tassie is just amazing!
I second the recommendation for Great Ocean Road. You can do it as a day trip in a small guided group - long day but saves you all the driving and means you get to stop at all the key points. I did this the first time I went to Melbourne and then when I went back, I hired a car and did it myself over 3 days. It was one of my most memorable experiences in Aus. Most memorable experiences ever actually.
Also second the recommendation for the penguins at Phillip Island. I hate tourist stuff with a passion but this was worth it. So memorable. I did the tour with a ranger. And again, I went back next time I was in Melbourne and did it again. It's mesmerising. I am still obsessed with those penguins (I watch them live in their burrows on an app...sad I know!)
I did a great coffee tour in Melbourne. Me, the guide and 2 locals. We went to some great tucked-away places, stupendous coffee (even by Melbourne standards). And I got excellent food recommendations from the locals too.
Sorry, I am addicted to Melbourne.
I used to live in Asia so went to Australia a lot (that's my excuse).
Still in/near Melbourne (sorry!), you can combine a visit to Healesville Wildlife Sanctuary with some wine tasting in the Yarra Valley. Or some wine tasting on the Mornington Peninsula if you're heading to see the penguins.
I'm less of a Sydney fan but visiting the Blue Mountains was fabulous. And of course the classic Opera House-Harbour Bridge view. Friends live in Manly and rave about it (but I haven't visited them there yet due to Covid - and before then because I was sulking that they'd left Melbourne lol).
Uluru was somewhere I didn't really want to visit. Back to that hatred of tourist stuff. I remember seeing it out of my plane window and thinking ok, done it, let's not bother landing. But actually it blew my mind! Standing watching the sunset with a glass of champagne in your hand and good company, that was a good start. And it just got better. I was there for 3 days/2 nights and that felt exactly right. Dawn at Kata Tjuta is also incredible. It's worth the early starts (and the long drop toilet experiences lol).
Shame you won't be in Melbourne for the F1 Grand Prix though.
You'll have an amazing time. and the memories will stay with you forever.