Me, my wife, parents and parents' friends (10 people) took a trip much like that. We were scheduled to depart from Hawaii for China on 9/12/01. We missed most of Beijing due to all flights being grounded, but were able to make it out to the great wall before being hustled back to the airport for the next leg of our trip. Spent about 5 days on the Yangtze river and saw some truly amazing things, some of which will never be seen again. They were still building the 3 gorges dam then, which we sailed past, visiting some cities and cultural treasures that are now underwater. I also remember how many low tech factories we passed...an industrial revolution right before your eyes. And coal barges! No surprise the most common ship on the river is the one that's powering the growth.
The tour guides do get a kick back from the shops. They will have an excuse at every stop to hang back while you get back on the van/bus. I thought our tour guide had some awful bladder problem until around the 4th stop, when I looked back over my shoulder just in time to spy her pocketing a small wad of cash. "Duh. Of course!!!". It's very much like Disneyland or Universal Studios; every attraction has at least 1 shop at the exit. Thus your goals are not necessarily aligned; you will want to see the best attractions, but the tour guide will take you where you're most likely to spend money. And of course every tour guide said their city/province/zone was the largest/most populous in the country.
It's one country, but many cultures. You can see the looks of people change as you move from city to city, working your way from the center toward the coast. The school children you see queing up for the bus tells a lot about the place you're in. The women selling tea and robes in the tourist shops in Chongqing and Chengdu are striking, with completely flawless skin. You miss them more and more the farther east you go
One of the things that made an impression, after days on the Yangtze, was how many homes on the river banks--basic concrete hovels housing poor fishermen and their families--were so poor they had mere openings for windows (no screens or glass), yet nearly all of them had a satellite dish on the roof.
It is a cultural shock but highly recommended. Do your research and stay healthy and safe. Lots of legitimate offerings, but some risk too. Though poor, the vast majority of people are honest, but just one thief can ruin your entire trip.
I've been there 3 times over 13 years and am always amazed at the cultures and the pace of change. I would always recommend a trip there. That said, my wife didn't care for it as much, as she thinks the country is too dirty and the accommodations too rough. While on the Yangtze cruise, she would stuff her purse full of steamed buns at breakfast, as she knew she wouldn't want to eat anything else that was served for the rest of the day.