My friend lives in Toronto and he spends 3-4 months each year in China. One of the problems he has is finding a reasonable place to stay for less than a month. As they say, "Neccessity is the Mother of Invention", his solution is to find partners in various Chinese cities who can provide short term accommodation. Some may even act as guides, teachers or interpreters.
I am helping him to find places in Beijing. A list of short term rentals can be found here:
http://www.cyber-courier.com/rent
***