Great Wall was famous in the world,and you know,it cross a few provinces,when you come to Beijing,maybe you know Badaling,Mutianyu,or Simatai Great Wall,but when you watched the Great Wall from TV,the pics all come from the section was named Jiankou!
From the downtown of Beijing---Dongzhimen Coach Station to Huairou District,6RMB,and then rent a car,the whole trip about 90---120RMB,Gate Ticket 10RMB!
You can spend two days in there,and live in the farmer's houses,about 10---40RMB/per.
Have a nice trip!

If you have free time when you travelling,and the chinese universities are best choice,because some of them are also a beautiful park,and free.I recommend Beijing University,Wuhan University and Zhongshan University!!!

If you go to guangzhou,zhujiang night cruises is not lost!!!and the price about 48RMB,2h.You can get on the ship on Dashatou Port,it is near the Guangzhou Binjiang YH.

Usually,when you come to beijing for travelling,and you will go to the Forbidden City,Great Wall,Summer Palace,Heaven Temple,Tian'an Men Square and so on!!!They are MUST SEE places.But do you want to know the other small,interesting and historical parks???I recommend Jingshan Park and Zhongshan Park.Jingshan Park in the north of forbidden city,and zhongshan Park in the west of Forbidden City,one is 4RMB,and the other is 3RMB.
Have a nice trip!