Hi, you could consider the hotel located in Qianmen, Wangfujing or Xidan around the Tiananmen Square, all of which are the transportation and tourism centers.
Since you want to stay with children together, so I think you have to lodge in a 4 or 5 stars hotel which has large room.

As for the itinerary, could you please let me know any special thing you want to do in Beijing? And, will you arrive in Beijing on 17th and leave on 23rd? If so, will you just have a half respectively in these two days?
17th: Tiananmen Square-->Qianmen Street(visiting shopping dining)
18th: Forbidden City-->Jingshan Park
19th: The Temple of Heaven-->Beijing Museum of Natural History-->free afternoon to explore the local life in Hutongs around Shichahai
20th: Badaliing Great Wall-->Beijing Nantional Centre for the Performing Arts-->Wangfujing
21st: the Summer Palace-->the Old Summer Palace-->Tsinghua Univeristy or Peking University-->Bird's Nest&Water Cube
22nd: Beijing Zoo&Beijing Planetarium-->Beihai Park-->walk to Shichahai again
23rd: you could visit a museum in the morning and leave from Beijing in the afternoon.

Just for your reference!

Thank you Mr Shan for your reply. We have confirmed our flights and hotel. We will reach Beijing in the evening of 17 Sep and shall leave beijing on a 9am flight on 23 Sep. Planning the itineary now. Thinking of exploring the surrounding of the hotel which is near Wanfujing road for the first day or visiting the bird nest stadium at night. Maybe you can help me by grouping those attractions that are nearby for a single day visit. Not too sure which are the ones should i cover in a day. It is the first time we are bringing the kids to China and we want them to see the major attractions in Beijing for this trip. TQ.

Hi loh, if so, I think you could walking along the Wangfujing Street with your kids in the evening of 17Sep. You could have a supper here. So, go to the Tiananmen Square when you go to the Forbidden City, both of which are located together. If you arrive at the hotel after 20:00 on the 1st day, it is not suggested that you go to see the Bird's Nest since you may miss the last subway if too late. Hope this helps!