I'm coming to Beijing for a visit in October. There's even a fellow Canuck I know who just moved back there...I'm hoping the 3 of us can meet up and DEFINITELY go to Wukesong (I need to get as much Era B&W paper as I can cart back home) as well as do some shooting around the city. I had really good luck just wandering the hutongs (you want to be careful not to shoot the demolition too much, especially as a westerner as it's perceived that you're attacking China by doing so, somehow).
I went to the Wall near Mutianyu last year in August...trust me, you don't want to do that in hot weather. I felt like my heart was going to burst out of my chest!
Anyway, let me know as I'm a die-hard film fan and would love to meet up.