Since I did exhaustive research prior to my trip to Beijing, here is my .02 on my experience there regarding tour guides.
All the guides I had contacted quoted me about 3000CNY for the 2 days of sightseeing in the city. I then read other posts, where people said that we CAN do the tour without a guide, and so I changed my search to a car/driver. Contacted many people offering this service and finally settled on Simon, and I did not go wrong with this one...while paying less than half for his services. At each location, he told us where to go and what to do, and even provided us with maps so that we could refer to it.
We travel extensively and if you look through my posts, we mostly do private tours, so for Beijing as well I chose Simon to drive us to Mutianyu, Summer Palace, Temple of Heaven, Forbidden City and then on the 2nd day, drop us off at the airport.
He was punctual and showed up at the hotel right on time. From then on, for the next two days, we were taken care of so well - it was good feeling, knowing that someone was there taking care of us and genuinely wants to ensure we are doing the right thing. Hubby wanted to get a SIM card for our phone, he called the telephone company ( I think it was China Telecom) repeatedly to make sure he understood the right plan that would work for us, and then helped hubby get it. Bottled water was available for us to use. At the Great Wall, he reminded us not to buy anything from the shops there since we can get it much cheaper at the Silk Market. When we asked him if he can come with us to the Silk Market, he could have easily agreed and made more money however suggested we go on our own since that will help us bargain more - and OH the deals we got :). At the sites, before we got our own phone, he gave us his spare phone so that we could call him when we were done and he would come pick us up instead of us walking around trying to find him. He took us to several authentic inexpensive restaurants where we were the only foreigners so that we could try the local food. Honestly speaking, he set the bar so high, we were a little disappointed with the guide service in Xian...
He did not rush us in any way, and on the 2nd day, when we were done with Forbidden City and Tiannamen Square, he suggested Pearl Market for shopping if we were interested. He took us there and waited while we shopped ( so much that we had to buy a third suitcase). He then suggested taking us to another location on the way to the airport, but we were tired by then and just asked him to take us to the airport. He was very professional while friendly at the same time.
Let me know if anyone wants his contact information, but I can, without hesitation say, you cannot go wrong with this guy. Wish I could find someone like him at every foreign city we visit.
He drives a Volkswagon Skoda which is very clean and it is obvious he takes care of his car and takes pride in it.