Here's an easy-going itinerary for a 2 week trip down under (mix of flying and roadtrip'ing) + my 10 top things to do! No AI used here either :)

I did it in May, during autumn/ winter season, but the weather was sunny and still fairly warm (around 10-15'c). Spent around 4 days in each place. Flying to&from Aus + the in-between internal flights add up to around 4days.

Melbourne:

1. Go for a walk downtown, with a coffee & a pastry in hand! I totally recommend Lune

2. Check out the Australian Open courts (you an also book a game as an experience)

3. Buy tickets for a very Aussie footy game, it's a BIG thing out there! https://www.melbournefc.com.au

4. Afternoon in the Royal Botanical Park

5. Drive to 12 Apostoles beach (day trip!)

Sydney:

6. Take a boat to see the city (not the toursity one, just the normal commuter boats will do & tap in, tap out for payment), best way to see most of the major toursity attractions!

7. Taronga Zoo (with the Koala bears ;) . Sadly (by law) you cannot pet them in Sydney, doable still up north of the country!

8. Bondi beach and the Bondi Icebergs Pool.

Sunshine Coast:

9. The simple pleasures: hang out at the beach (+surfing if you're brave;) at Sunshine Coast

10. Day trip to Byron Bay

And my special bonus (number 11;) - just have a cold beer, in one of the bars by the Opera House in Sydney, overlooking the port and the Harbour Bridge. Core memory from this trip!!!