If you ever get the chance to drive the great ocean road just do it.. Its an amazingly easy and pleasant drive from Melbourne city, and while you can take a tour bus, I just feel nothing quite beats the freedom you have to dictate when and where you will be.
Just be warned that the water is cold :P, and when I was there, Melbourne and Victoria were plagued by flies!!! These suckers will and do fly into your mouth, ears and nose.