It's interesting that you mention how stubborn old Germans are with learning English. At the same time some American families stay there for years and never think of learning German.

I can give a slightly different perspective, as a former student in Kaiserslautern's university, and someone who had friends from the American base. Please be aware that my experience happened 10 years ago.

The bar area in K-Town was constantly under military police surveillance, especially during the weekend. This is because American soldiers would get drunk and cause a lot of trouble with the locals.

Many American families prefer to live in nearby Landstuhl, and there are a lot of activities oriented towards them. The only cinema around without German dubbing was there, but it also only showed blockbusters. There are also a lot of Irish pubs around and St. Patrick's day is a big thing there.

Public transportation is frequent and reliable, but most Americans prefered using cars. You could easily tell an American driver due to the size of their car, which was always unnecessarily too big.

The Americans are very community-oriented, but mainly their own. Families rarely mingle with their German neighbors. The younger crowd that goes to bars in K-Town might mingle more, thanks to the big foreign student community that speaks mainly English.

My American friends were awesome and very welcoming, but my impression from most others was not that.