Nighttime is the time to be out in Guiyang. The city is a lot more attractive once the sun goes down and, generally speaking, has a better atmosphere too. Guiyang人 have a reputation for getting up/ starting work a bit late, and going to bed late too. As a result, its fun just to walk around.
Also good:
-Night market street food. From about 6元 you'll get some tasty stuff, and its more enjoyable than expensive restaurants a lot of the time.
- Coffee shops. Guiyang has increasing numbers of places that serve coffee.. some good, some bad, some just OK. I personally like the Createa chain (cheapish, busy, nicely decorated) and highlands coffee for its genuinely good tasting coffee (rare round here) and delicious cakes etc.
- river.. that area is pretty cool. Have a beer on at the pagoda (Jia Xu Lou.. can't remember the name) sadly they only serve "snow" which isn't the best Chinese beer.

In the years I've been here I've noticed at study increase in the number of pickpockets in this city. Don't get me wrong this is a Great place to live and really a very safe place to visit, just be careful. Especially near the train station and the main traffic circle (penshuichi)