We made this trip this weekend also. Excellent drive went from Torque to Port Campbell and overnighted at the 12 Apostles. We then took the inland rout back with some short day hikes in the Otway National Forest. Excellent trip, but it should be noted that if you suffer from car sickness this road will get to you. This was a rough one on my wife, she ended up driving most of the curvy sections at a relatively slow pace, but it was worth it.

ohh - and if you do overnight on the road, make sure to set aside some time to star gaze if the night is clear. Unbelievable views of the Milky Way without the light pollution of the big city.