A:Got it—a lightweight hiker for hot weather, some trails, and a lot of city walking. What are you going be doing in China?
Anyway, several good choices out there. I'd probably go with a mid-height boot, one that's breathable and light. A good example of that is the Keen Targhee II Mid ($125). Sort of a super trail-runner, with a slightly high-cut boot with uppers made from nylon mesh and nubuck leather for good durability and breathability. EVA midsoles are right out of the running shoe book, with good cushioning on hard surfaces. And nylon shanks for flexibility with decent stability. A very similar show is the Oboz Yellowstone Mid ($130). I also like the Sawtooth ($135) its outsole has exceptional grip.
The Merrell Moab Ventilator Mid ($95) was absolutely built from the ground up for hot weather. It's also a mid-height boot, but its uppers are about half mesh, with leather as well. No waterproof bootie like you find in the Keen and the Oboz; the Moab is all about breathability in hot weather. It also has an EVA midsole, air pocket in the heel, and grippy Vibram soles. Really a nice shoe for hot weather.
In a low-cut, a good choice might be Lowa's Tempest Lo Women's ($135). A tough shoe, designed for warm, dry weather, with leather uppers and a polyurethane midsole. And they'd look and feel a little better around town than mid-height shoes, although I still like mid-heights for trail use.
Have a great trip!