You have to stop on the way to Kashgar so might as well check out a few places enroute.
Urumqi is a practical jumping point and is good for a day visit. we stayed in People’s Park, walked around the Bazaar and visited the museum. Rented a car and drove 2h to Turpan. Good for another night or two. June, so 40c + !!!! Stayed in Grape Valley in a cool mingsu with context and some great grapes / raisins! Interesting visit to the ancient ruins of Jiaohe/Yarghul, the capital of the Tocharian kingdom (108BC), the very nice Emin Minaret / Sugong Tower 1778 and Tuyugou old town in a valley of the Flaming Mountains plus a winery to finish it off!. Easy drive back to the airport and a flight off to Kashgar.