Wilsons Promontory in Victoria is a must.
See here for deatils http://parkweb.vic.gov.au/explore/parks/wilsons-promontory-national-park
I took the family here last year and we think it is the best place we have camped at.
At dusk many kangaroos and emus can be seen, on the road leading into the camp area.
At the camp area we went Wombat hunting at night with outer people we met at the camp site.
Very early in the morning I took a walk and saw a deer. I didn't know there was any in the area till then.
There is also the beach, the native plants (which I love) and the wonderful birds.
Plenty of facilities, plus a little extra in an outdoor cinmea.
Along the way stop off at Philip Island.
We stayed at the Big 4 caravan park. The location was good. Not far from the beach.
At night we watch the penguin parade. An amazing site.
My favourite thing to do is to laze around on the beach eating fish and chips, while the kids played in the sea. My wife put a chip on my head and I was instantly attacked by many seagulls. I had not seen so many seagulls before.
The wildlife santucary at Philip Island is great way to spend the day, or a walk at the Nobbies, to see the blow hole. Now I've never seen so many seagulls in my life! There were so many the sky was obscured.