Wild China is a travel company that specializes in eco-friendly, sustainable tourism: "WildChina is China's leading cultural and sustainable tour operator. WildChina offers distinctive, ecologically and culturally sensitive journeys to all corners of China." They offer the broadest range of tours that I've come across in China from student, family travel and tours to corporate events. Wild China was founded by Yunnan native Mei Zhang and the company is managed in Beijing. It has an extensive and loyal set of guides and I have only heard very good reviews from people who have used them.
Wild China has an extensive web site (www.wildchina.com) so that is a good place to start if you don't know exactly what you want on your itinerary. Their staff are some of the most helpful I've ever worked with (and I haven't actually traveled with them yet) so begin by emailing your questions. A staff member will contact you and you can begin to tailor your itinerary. They also have group tours leaving on set dates with pre-set itineraries that you can join and tour themes range from "classic" travel to "immersion" and "adventure".
From their website: WildChina accepts U.S. dollar denominated personal checks; credit card payments via Visa, MasterCard and Discover; and wire transfer.
Don't be immediately put off by costs:
When looking at Wild China's web site and the tours they offer, you may quickly get sticker shock. Wild China is certainly high-end but, like I always say, you get what you pay for and everyone I've interviewed after a trip with the operator has been overwhelmingly positive about their experiences. If you like to do a lot on your own - and big cities like Shanghai and Beijing are relatively easy to conquer without a guide - look at supplementing your trip with a tour to an area where having a guide and driver would definitely enhance your experience, for example in Xinjiang, Tibet and Yunnan.
My thoughts on taking organized tours:
Read a full discussion about my thoughts on taking organized tours here.