Can Americans travel to Beijing & book tours once they arrive?

Hi, it may be a little complicated and inconvenient to get a tour upon your arrival. So I suggest you book one in advance.
I recommend you turn to TravelChinaGuide for the tour information in Peking. I used the travel agency in Oct. and got very impressed experience.
Here is their email address:
travelchinaguide.com|tours

May help, dear!