Perfect (hot, but not as hot as July & August) weather.
Beijing is a lovely old city (except for the horrible new parts from the Olympics), so it's worth taking the time to explore it. By foot, start in Tienanmen Square.... you can see Mao Tse Tung's Tomb & a few other buildings in the Square. Cross the road at the far end to go to the Forbidden Palace - an amazing place to see, which takes a couple of hours.
Also worth a look is the Temple of Heaven. There are many amazing and beautiful places in and around Beijing for sightseeing. Google Beijing for more info than you can poke a stick at! over 5 years ago