A Chinese friend told me that the reason I was having trouble talking with people in Beijing about 三里屯 is that I did not use erhua. She told me no one in Beijing will recognize it unless I say sanlitun(r). And she was right, of course. But I did not ask her at the time, is erhua standard (for Beijingers) on 村 in 中关村?
As a Beijinger, I'm pretty sure there is no erhua on 村 in 中关村.
Normally, erhua is for the small locations or things.
For example, there is a landmark spot named 前门. ALso 前门 is the same word which means the front door. When saying 前门 with erhua, 前门儿，it means someone's front door. And without erhua, 前门, it means the landmark only.
Similar situation with 村，As 村's original meaning is village. Then when someone says 村 with erhua, it usually means some specific village.
Of course, as a lunguage, there always be exceptional situation, like 三里屯. People use erhua with it to present the landmark.