US , Canadian and EU Citizens do not need a Visa if they visit any Schengen countries (Western European Countries part of the Schengen agreement)
Turkey (and Israel) gives US citizens visa upon arrival.
If you are an Isareli citizen its different and I dont know the Visa laws
About Safety for jews in Europe, Ive been there a few times including Germany and did not feel unsafe at all. In fact the first thing I saw in Germany was a Kosher food Machine.