Just be aware that credit card acceptance is still relatively low in Europe, especially Germany, compared to America, and not all cards are accepted. I was actually surprised last week to find places in Paris no longer accepting Amex - places where I have dined in past and paid via Amex. And VS and MC charge a foreign exchange fee, so while Amex is the best for fees, it is not always accepted.
In Germany a lot of stores such as grocery stores accept 'credit cards' but they only accept the EC card, not MasterCard, etc.
Also US issued c/cards won't work in many machines around Europe ie ticket machines, parking machines, postal machines as they don't have a chip. (Sorry, I may have already said that!)