Hiking 15 Sept? Also a group Consul for Hiking BJ (Beijing)

Guys, I'm thinking of an activity for 15 Sept, the next Saturday. But at the moment all the best places for autumn I can think of require bus rental. Since we don't have any pre-pay / guarantee system here on Internations, (and most importantly, there are people who prefer "no show without any notice" in the past), I'm kind of stuck here for places we can go by public transportation... Any suggestions?

Also if anyone is interested in being a group consul for hiking Beijing, please feel free to let me know. For safety reasons, it's really hard to take a whole group of people to the wild mountains here in China so if anyone who's familiar with the hiking routes around Beijing could help me out, it'd be really appreciated.