I heard from a friend who works for an forigen exchange company in China is the best place to do it is outside China.

This is mainly due to the fact that the local banks and exchanged bussines don't have as much access to forigen currency as the government has.

Also I would avoid airports……. Although they have good exchange rates after commission is is hardly worth it.

I would suggest asking various banks ask what there rate is and how much commission they charge.

Where?

I find the rates inside China fairly leveled. The rates between airports, banks, hotels don't vary too much. So it doesn't really matter too much where you change.

Hong Kong is good too, in theory. In practice your US$ will first be changed to HK$ and then to RMB. You need to check that you don't lose too much on the US$>HK$ transaction.

Check also with your credit/debit card about the ATM withdrawal charges, that is a good option too (at least for some cards)

I just came back for my trip, here is the conclusion from my exp of my trip last week and trip 2 years ago:

1. The bank inside China has the best rate, but it is painful to wait on the line. It may be a little bit faster if you don't look like a Chinese. Bank uses standard rate, you cannot bet it. It is the safest place to get money.

2. The hotel has a pretty good rate. Fairly close to the bank's rate - at least for the one I stayed in, but this could be different from hotel to hotel.

3. Use your USD debit card - Bank of America align with China Construction Bank that allows you to withdraw RMB in China without additional charge. Commerce Bank ATM card does not seems to charge any extra as well (I just used it in my trip. The monthly statement does not have details about the rate, but I calculate it. It is about the standard rate of the date.

4. Credit card usually have a 3 to 4% subcharge.

5. Exchange store at airport has a very bad rate.

6. Never exchange currency with unknow source in China, there could be fake. Watch out the case like you pay some the 100RMB, and the guy returns you telling they don't have change. They may have already exchange the bill to a fake one.