Where have you been in China?

I have been to: On travel: Beijing, Xi'an, Lanzhou, Xiahe, Yangshuo, Suzhou, Hangzhou, Xiamen, Chengdu (and lots of small cities in Sichuan), Anji, Huangshan On work: Shanghai, Shaoxing, Wenzhou, Ningbo, Dalian, Yantai, Chongqing, Guangzhou, Shenzhen Of the places I'd really recommend seeing -- Xiahe and Huangshan I've never been to the far west (Xinjiang), Tibet or the far north... Anyone been up there?