Originally Posted by moondog

There are a few overnight z trains between Beijing and Xi'an that could be of interest. Between HSR and flying, I'd go for the latter both in and out of Xi'an because it's cheaper, faster, you can check bags, and you avoid dealing with train stations. However, if you're really keen on experiencing HSR, Beijing-Xi'an is probably the best candidate during your trip (shorter than the other legs and lots of trains).