From Chengdu to Lhasa, there is only one train operating, and it passes by around 7 places on the route by costing around 43hrs. While on Golmud-Lhasa route, there are several trains in operation. Among them, the ticket price on train K917, K9801 is cheaper. For the comfort degree, it depends on which berth/seat type you choose. Usually, the soft sleeper is quite comfortable.