If it's a private school you shouldn't have a probelm. If they went around cancelling visas it'd be really bad for business. For the last couple of years i regularly attend class for the first couple of months, then somehow get lost on the way to school after that...
However, if you're at a University it may be slightly different. I've heard from friends that some of the Uni's are a lot stricter on attendance.
A couple I know are coming to Yunnan on holiday. They'll have around 3 days to spend sightseeing in Lijiang and Shangrila. Money isn't really an object for them (lawyers!). I haven't really done much sightseeing in those areas except for Tiger Leaping Gorge and Deqin, so any other recommendations would be great.
Also, does anyone know of any services in those areas which supply a translator/guide? My friends aren't looking for any package tours, but someone who can accompany them on what they decide to do, and either tell them about the area/place/thing, and/or translate if they run into any difficulty. I'm kinda busy so can't go with them to help.