Hi Neil,
You can go to any travel agencies websites, like Tak Shing, Hong Tai, Sunflower, etc. they offer tour group. This include your hotel and breakfast buffet , lunch and dinner plus a tour to forbidden city, Tianamen square, Emperor's Palace, Summer's Palace, Terracota Warriors, or Great wall. It will be more cheaper if you join a tour group and you will meet more friends.
Though, if you want to have a free time by yourself, I suggest you buy a map and explore it by yourself by taking the taxi or trains which everything now is accessible now in Beijing esp. they are very modernized now after the Beijing Olympics games. I have been there 4times but too bad I did not learned their language at all and now trying to learn it.
Hope you will enjoy this trip,
Jackyine