I travel to China on average each month, but until this month, had never visited Beijing. I'm familiar with Hertz driver service in Shanghai and Hong Kong- so I used them in Beijing for airport transfers and travel to MuTianYu. This will cost you considerably more than a taxi, but for a short trip to Beijing, I'd highly recommend them.

For the airport to hotel (and back again) you can reserve a dedicated driver who will have a sign with your name printed on it who will meet you at the airport (and at the hotel, too). For any of the Great Wall sites, you can reserve a Hertz car and driver to take you, wait for you, and take you back again.

In our case, the cost of the trip to MuTianYu covered the driver for 9 hours. We had started at 1:30pm, so after the Great Wall, he kindly took a path past all the Olympic sites (all lit at night), then to our hotel. All of this he offered to do. After return to the hotel, he waited for us at the hotel, then took all of us to and from dinner. He knew MuTianYu very well and helped us find the best way to the top.

I'd highly recommend this for a quick visit- confirmed dependable, don't need translations- could be good idea just in case- can pay by credit card.

You can find more on Hertz here: https://www.hertz-europe.com/rentaca...tedRegion=Asia
This page talks about luxury service with Mercedes and such, but they also have more modest accommodations. My wife and I had Camrys for airport transfers. We and our friends had a Buick for the MuTianYu visit.

Have a great trip!