Well, as you can tell, I am really enthusiastic about it. I had a wonderful time - the best vacation I have ever had. The guides and drivers that this China travel agency arranged were great, and all of my flight connections were good. The guides were willing to be flexible and accomodating (one of my friend's flights was delayed, and the guide waited with me about 2 hours for my friend to arrive - and never complained at all). I was very pleasantly surprised that all of the connections went so smoothly, since my itinerary was pretty complicated. Each of them treated me so well, and all at least pretended to be impressed that I can speak and read some Chinese.
Oh, there were so many things! Meeting my friends there was certainly the best part of the trip. Everyone I met was wonderful and so hospitable. The sightseeing was great - China is absolutely fascinating. It's definitely a little rough around the edges still, as far as what a American tourist might expect. The food is great (if you like Chinese food), but the restaurants aren't always exactly spotless. Away from the hotels, the bathrooms are, um, "unusual." But I was prepared for that and didn't expect 5-star accommodations, anyway. On the other hand, the museums and other sightseeing locations were amazing and wonderful - every bit as interesting and incredible as you might have heard. I don't know if I can pick a favorite place; they were all (Forbidden City, Terracotta Army, Summer Palace, and so on) really great. One of my favorite parts of the trip was that I got away from many of the "tourist" places, since I was able to meet Chinese friends there and travel with them. In Changchun and Kunming, I was with friends the whole time, so I got to go to places Westerners typically don't go (Palace of Manchukuo Emporer in Changchun, the Stone Forest and Minority People's Village in Kunming). I am definitely looking forward to going back to China sometime - hopefully soon!
The only thing I would do differently is to take a little more time in each place and not try to do so much in one trip. I could easily have spent a week in Beijing, but I only had 3 days. I think doing northern and western China (Beijing, Xi'an, and so on) separately from southern China (Kunming, Hong Kong, Shanghai) would make the trip a little easier, and maybe less costly (less flying!).