I can highly recommend the Yarrangobilly Caves area. Beautiful country to drive in, lots of animals, and there are thermal pools and bushwalks to go with the many caves. I stumbled upon this place and it was a real hidden gem. Do try to arrive early as you need to reserve tours for each cave (I only went to one cave, and enjoyed walking and swimming in the pools the rest of the time).
https://www.nationalparks.nsw.gov.au...rmal-pool-walk
You could drive through Adelong on the way from Canberra, and visit the old gold mill ruins.
Adelong