It depends what you're interested in… There are nine sections of the Great Wall near Beijing City. The most recommended section for foreign visitors is the Mutianyu section. It is less crowded than Badaling's Great Wall, which is extremely popular with Chinese tourists. The Jinshanling section and the Jiankou section are recommended for hiking tours. For camping experience, Jiankou and Huanghuacheng are great options. The Simatai section is the only one open at night... and beautifully lit.
1-Day Jinshanling Great Wall Hiking
1-Day Jiankou Wild Great Wall Hiking
2-Day Mutianyu & Simatai Great Wall Day-Night Tour
2-Day Jiankou Wild Great Wall Camping Tour