I'll be traveling to China for my first time this summer; I'll definitely be in Shanghai and Beijing for work, but I'd like to get out of the cities for a few days and do some trekking and sightseeing. My work trip stretches for two weeks, but I'll probably take some vacation days on one or both ends depending on how the trip works out. So I have a free weekend between Friday afternoon and Monday morning to fill, as well as some days before or after the work trip.
Is Lhasa feasible to do over a weekend? Are there any day treks that are accessible from there? Or should I plan to visit Yangshuo/Guilin over that weekend and go to Lhasa from Beijing after work ends?