Xi'an's city wall by bike, and Chengdu's pandas before 9

Xi'an's Ming city wall is a 14-kilometer loop you can cycle in about two hours on a rented bike at the top; sunset from the wall is the city's best hour, and the Muslim Quarter below is for dinner. In Chengdu, the Panda Base is best at opening, when the pandas eat and move before sleeping through the day. Guilin's river to Yangshuo, Zhangjiajie's stone pillars, and Yunnan's old towns are the natural wonders beyond the big cities; domestic flights are cheap and frequent.