Instead of overpaying for a SIM at an airport counter or wasting time looking for a shop where they speak some English and trying to figure out the right package, it is better to just pre-order online from China Unicom and get it delivered to your hotel: https://www.mychinaunicom.com/toProdisplayPage.dhtml
Obviously, the frequent travelers to China or locals will not go this route but this simpler for the occasional tourist.