Which way is best, from Portland or from Melbourne to see the best sites on the Road?
If you originate in Melbourne, all your turn-offs will be on the left-hand side. Getting back on the GOR will mean an easy left-turn. The only exception will be the 12 Apostles. If you head west to east, you might have to wait several minutes for an opening to make that right turn back on the GOR.
+1 for deSchenke.
Portland is not on the GOR. Most people only go as far as Warrnambool (which is also not on the GOR but is not far past it and has lots of great sights in its own right).
How long do you have for your trip?