Gate1 Travel is a US based company that offers an “Air and Land” option as well as a “Land Only” option for their tours. They have several tours to China (https://www.gate1travel.com/asia-pacific/china-japan).

I used them for my 1st trip to China, which was back in 2010. But since then I have travelled in China on my own, including to places like Lijiang in Yunan, which is a bit off the beaten track for western tourist. I never had an issue travelling on my own in China, except when I was leaving China at the Xian airport. The Chinese immigration officer skeptical that I was travelling by myself.

I have also used Gate1 for tours in other places, like Morocco and the former Yugoslav republics, and always been very happy with their service. I also know several of my friends who have used Gate1 and they too are very happy.