Be especially careful driving within speed limits throughout Victoria as fines are very steep and radar and laser speed traps are common.
The Great Ocean Road is a beautiful scenic drive, right around to Port Campbell National Park. My favourite places to stay along that drive are Apollo Bay (pretty) and Port Fairy (pretty and historic). Good landscape shooting at the 12 Apostles/Loch Ard Gorge/Port Campbell National Park, particularly around sunset. Make sure you see the very small, historic cemetery while you're there. Take care on the cliffs, the southern ocean is dangerous and waves can sweep over the rock platforms.
In the other direction along the coast, Wilsons Promontory National Park is a wild and beautiful combination of beaches, mountains (well, only just) and forest. Book accommodation in advance at Tidal River through the national parks service (it may be booked out due to Christmas holiday season).
I like the picturesque historic gold fields villages and towns in central and northern Victoria; and often you can often find a winery nearby. Victoria had a gold rush similar to the California gold rush, and the legacy is a scattering of pretty, historic towns like Daylesford, Maldon and Beechworth, as well as larger wealthy centres like Ballarat and Bendigo where gold money built fine civic buildings.
I personally like the Victorian high country, starting at Beechworth or Bright, a side trip up to the Mount Buffalo plateau (great views of the main range from The Horn), then drive over the main range through Mt Hotham and Dinner Plain to Omeo, and then back down to Melbourne via Sale and the coast road, with a side trip to Wilsons Prom.
If you like wine, the vineyards of Rutherglen and Milawa are nice places to visit, but locals might point you to more accessible wine growing areas near Melbourne like the Yarra Valley, which I haven't visited.
The good thing about Victoria, is that distances aren't that great by Australian standards, and there is so much to see.
Just remember my caution about speed limits, and take care on the roads.