I've planned out my entire Australia trip now with everything booked EXCEPT 1 night. I'm deciding whether to spend 3 days in Melbourne and 6 in Sydney OR 4 days in Melbourne and 5 in Sydney.

So... whether to split 3/6 or 4/5.

Here's the trip:
- arrive to Adelaide
- 1 night in Adelaide
- go to Kangaroo Island
- 2 nights on Kangaroo Island
- 1 night somewhere on the Great Ocean Road
- 3 or 4 days Melbourne
- 5 or 6 days Sydney
- 5 days Golden Coast and surrounding area

As I want to book a MEL-SYD ticket today, I'd really appreciate some opinions...

We like walking around the city, just taking it slow, looking at the sights, maybe even go outside of the city... Very flexible without any rush that we absolutely must see something.

The night in question is December 27 - December 28, so if there's something cool going on in either city it might also be a factor?

Thanks a lot!