I will be in Beijing October 1st and just found out that it will be very busy because of the parade.

You can tour around Great Walls. After Oct.1, most scenic areas will open normally. You can visit Forbidden City, Wangfujing Area. Have fun!

You can check out some Hutongs, they are the old alleys that have been renovated and commercialised, such as Nanluoguxiang and Wudaoying. Also, Houhai, which is a lake, could be fun to go. If you'd like to visit somewhere modern, you can try Sanlitun, that is a shopping area with lots of bars and clubs. Have fun!