Classic route idea
A strong first route might start in Sydney, add the Great Barrier Reef or Melbourne, then cross to New Zealand for Queenstown, Milford Sound, Wanaka, and a South Island self-drive. With more time, add wine country, Rotorua, Abel Tasman, Tasmania, or a luxury lodge stay.
The right itinerary depends on the season and your travel style: active hiking, scenic drives, food and wine, family-friendly wildlife, adventure sports, resort time, or a softer luxury pace.