I'm surprised no one has posted Victoria, Australia's "Great Ocean Road" as a great drive. It is, but it suffers from tourists and their driving antics, or rather, their lack of concentration on their driving. To my mind the best part of the GOR is the western end, nowhere near as many "Sunday drivers" and, mostly, a 100 kmh speed limit.
The Western End, thanks Google Maps!
It's the perfect day trip from where I am, going out on the northern route, a bite to eat at Apollo Bay, fish and chips on the foreshore, a quick nine holes if you fancy it and home on the southern route. My only problem, SWMBO gets a little nauseous with all the up, down and around so I drive it solo more often than not.