Motorcycle trip through the south. So, I've got a four-day weekend coming up and a friend and I want to spend it on the road. We will be leaving from, and returning to Phuket on 600cc bikes. Does anybody have any advice on where we should go? Road quality/beauty is a greater concern than destination. 

I'm not interested in hearing about how dangerous this is, I have a decent amount of experience with motorcycle driving in Thailand, and fully understand the risks.