China built the world's largest high-speed rail network from almost nothing since 2008, and it is now the best reason to visit multiple cities in one trip. Beijing to Xi'an is 4h30, Beijing to Shanghai under five hours, Shanghai to Hangzhou under ninety minutes — all in clean, punctual, comfortable carriages that land you in city centres.
Book through Trip.com or the official 12306 app, both available in English, and carry your passport — you need it to purchase a ticket and to pass through station security, which functions much like an airport.
Domestic flights fill the gaps the rail network has not reached, including Zhangjiajie and Lijiang from most other cities. They are cheap and frequent but delay-prone, especially in summer thunderstorm season.
Within cities, metro systems in Beijing, Shanghai, Hong Kong and Chengdu are extensive, cheap and signed in English as well as Chinese. Didi, the local ride-hailing app, works well once linked to a foreign card, though having your destination's address in Chinese characters ready helps enormously since most drivers cannot read romanised pinyin.
A car is essentially never the right choice for a foreign visitor. Chinese roads use different rules, signage is overwhelmingly in Chinese, and every destination in this guide is reachable by rail, flight or metro.