From my experience recenly, sion take a a first-class bus (one with 16/18 seaters) for golden miles. It is comfortable and clean, take about 4 hours to reach KL. In the bus they supply a pack of makan and free flow of drinks (coffee, tea and bottled-water). Each seat has its own mini tv which you can play games and see shows esp musical type. I watched one musical and before I know it, I was in KL.