I don't think it's necessary to do a group tour to Australia at all. We spent 3 weeks in Australia in October 2024, and then we continued on to New Zealand for another 3 weeks. I planned our entire trip, and it was actually quite easy. We did have a rental car in Australia and NZ; my husband had already driven in Scotland, so he wasn't nervous about driving in Australia or NZ.
We had glorious weather in Australia in October. Most days were sunny with comfortable temperatures for sightseeing. We had very little rain. And very few crowds. Of course, it's always busy in cities; that's to be expected. And prices for accommodations were very reasonable. Our itinerary included Melbourne, Philips Island for the penguins, the Great Ocean Road (a highlight), the gold rush towns of Bendigo and Ballarat, Bright (in the Australian Alps), the Blue Mountains (spent 2 nights), and Sydney. Our itinerary was a little bit personal. My husband had lived just outside of Melbourne when he was a teen-ager (in the 1960's), and he has relatives there. So we spent the first 4 or 5 nights just outside of Melbourne, in addition to downtown Melbourne later on during our trip. We visited Bright because he has fond memories of going to camp there. While Bright is beautiful, it probably wouldn't be on most first-time visitor's itinerary.
Since you do have the time, I highly recommend spending 2 or 3 nights on the Great Ocean Road if you are planning on visiting there while in Melbourne. This would be a much more enjoyable visit than visiting for a day. I also feel the same way about the Blue Mountains if you are going there. We enjoyed this area so much more by spending 2 nights here.
Are you interested in Brisbane? We didn't have time to visit, but friends of ours loved Brisbane.
If it's in your budget, I would recommend flying Premium Economy for comfort. We usually fly economy, but for these long flights we chose to splurge on PE seats, and they were well worth it.
Many of our accommodations outside of the cities were in motels, which is quite common in Australia and NZ. All of them, except for one, were wonderful. Very large, updated, clean, and in great locations.
Want to add that we flew from Melbourne to Sydney.