2-3 week tour of mainland china from 21st of sept.?

My husband and I will be in Hong Kong from the 20th of sept. 2014. We would like to join a small group tour of the mainland which included Beijing, Xian, the Yangtze River, the pandas in Chengdu, and Guilin, for a 2-3 week tour. Could you tell me if this is possible? If so, how much would it cost?
I am also interested in the Silk Road, but I notice you don't combine the pandas, and Xian with your Silk Road tours.....