I'll be spending a few weeks in China: 6 days in Beijing then a fast train to Xian. Xian for 4 days or so then either train to Beijing then train to Datong or a train straight to Datong from Xian. I know the train to Datong is slow, but it seems to make sense to go straight there from Xian rather than go to Beijing and spend a night then go the next morning to Datong. I welcome any advice on my plans. Thanks!