My +1 and have visited Beijing 5 times, three of which were leading groups of Year 12s from Perth. We had about 7 days each time and saw all the main attractions:
· Great Wall at Badeling, Mutianyu, JuYong Pass or Simitai. My +1 recommends JuYong Pass for ease of access and smaller crowds.
· Forbidden City which could be combined with Mao’s Mausoleum, the Great Hall of the People, Tiananmen Square and the National Museum of China
· Temple of Heaven which can combine with the Pearl Market which is opposite the East Gate. (The Temple of Heaven is the largest religious enclosure in the world. It also features groups doing ballroom dancing, craft, mah-jong, cards, matchmaking, gymnastics, revolutionary dancing and singing.)
· Summer Palace
· Prince Gong’s Mansion and Hutong ride
The students had a free day built into the itinerary and most went shopping (at the Silk Market, now apparently closed).
This would easily fill up your days.
Some other options are:
· Military Museum on Chang An Dajie, which also features a few Terracotta Warriors plus chariots and horses.
· Houhai Lake
· Wangfujing and Snack Street
· Ming Tombs
· Coal Hill behind the Forbidden City
I hope you both have a fantastic time.