GUILIN, China—More than a millennium ago, the Tang dynasty writer Han Yu said of Guilin’s landscape, “The river forms a blue-green silk ribbon, the mountains are like jade hairpins.” Today, the scene in China’s rugged south is inspiring more than just poets. Economic planners see the potential for Guilin and other destinations to drive growth. China’s latest five-year plan, released this year, calls for making the nation a “tourism powerhouse.” Tourism checks a lot of boxes for Beijing’s planners. It is a way of encouraging Chinese people to spend when many are holding back amid slowing economic momentum. When foreign tourists visit,…