600km in a day is nothing.. I did Albany and back in the wagon, same day
I'd be more than happy to do a day trip to Albany again, the roads are quite nice and if we left at say 8am, that would leave enough time for a nice lunch and then on the road to get back to Perth before dark.
I like long drives, but Brad, remember our last hills run together? I'd like to do it again but minus the stone chip