Did the GOR on the honeymoon in the late 70's. Great road, but the car was only an LC Torana with a choked 2250 litre 6cyl and 3 on the tree! Wifey got a bit nauseated so all the driving fun was gone. Stopped in lots of places and even got to walk out over the London Bridge!
Did it again in the Lib a few years ago (2005) and was a crawl in peak hour like traffic. Too popular and almost too dangerous with many impatient overtaking manoeuvres on both sides of the road and a lot of buses, mini buses and tourists who obviously don't normally drive right hand drive cars on the left side of the road!!!.
So, I am guessing the best time of day will be very early morning, but then the furry friends come out to play!