Lanzhou is a very polluted city. It is also very large. Because it has no subway or effective mass transit system, getting around is a major pain. Many people fly into Lanzhou to start trips for Silk Road sites, to visit Bingling Si, Xiahe, Labrang Monastery, Xining. But staying in Lanzhou is a pain and not very nice. I recommend spending as little time here as possible. There are fantastic sites to see and things to do in this part of China. Don't get stuck in Lanzhou.
Unique Suggestions: Avoid the city center. Staying in a central location means long travel delays where ever you are headed. Instead, try staying on the outskirts or close to where you are heading. It is not a city for tourism.
Fun Alternatives: The airport near Lanzhou is a good 80 minutes away to the north. If you are travleing onward, maybe you could avoid staying in the city entirely.
Not trying to gross anyone up but at every public toilet cubicle, there's a little basket by the side. It's for you to throw i the used tissue after # 1 or #2's. If you accidentally throw the piece of tissue into the toilet bowl, chances are you'll see it floating there after a few flushes. The local only warned me about the toilet thingy on the second day *embarassed* Also another warning, some public toilets, DO NOT have doors.
When I travel, I love to sneak into backside alley to see something different, this is one of the special in Lanzhou, it's a trap to me, I was addicted to this kind of trap.