I think the Mornington Peninsula, south east of Melbourne is absolutely brilliant. The scenery over Port Philip Bay on the western side is gorgeous, the views on the eastern side to Westernport are also very nice.

It has some excellent wineries (like T'Gallant, Willow Creek) and winery restaurants that are excellent with nice local produce.

Great Ocean Road - as an Australian but a proud New South Welshman, even I think this is spectacular. Get a decent car though, it's far less fun otherwise.