I want to spend about 7-10 days in China with kids but don't know where to start.

For 7-10 days, you can spend in Beijing, Shanghai (Hangzhou) and Xian. To visit these attractions in Beijing, you can stay near Tiananmen Square, the center of the city. Roam around the square and see the Forbidden City first. Then head for Deshengmen to take a bus or North Rail Station to take a train to Badaling Great Wall. For other recommended scenic spots in the city, they are Silk Street, Zoo, Temple of Heaven, and Summer Palace.