Hi, I wil have a little bit less than 8 hours at Beijing, until my connection flight.

Well, your transit time is limited. In addition, that period is just the peak hour. So you are not suggested to go to downtown area. You can find a restaurant or cafeat the airport and taste some local foods. In addition, there are also many shops for your entertainment. But if you insist in taking a short visit in downtown, go to Wangfujing or Silk Street. Hire a taxi for the round trip in case.