6 hours transit in Shanghai airport, any suggestions to kill time

Hi, I will be flying home enroute returning to Singapore, from Seoul via this city sometime next month. My flight transits for 6 hrs. That is pretty long transit and I have intention to get out of the airport to sight see. Any recommendations for a quick trip to the city from the airport. Can someone tell me how, bus or train? or any organised trips from the airport itself. Any other info, will be appreciated.