When I lived in Europe from 2002-2005, some of my friends' families declined to visit due to fear of their safety and this was Switzerland!
I never felt unsafe in Europe...you just go on with your life and don't think about it.
I have had similar thoughts about visiting Israel and have not done so because of safety reasons. However, those who have visited or lived there, say that my perceptions are also false. So, we all fall into this fear based mentality. And, that is what terrorists hope for and why they are successful.
THink about Turkey. How many times was Turkey cancelled from cruiselines' itineraries? When we were in Turkey, I never felt unsafe.
So, I try not to overanalyze and go with the flow. As far as a cruiseline, they have to watch out for their investments and would not send us somewhere that is unsafe. If they keep a port, I feel that we are as safe as can be predicted.
It is sad that these nuts are everywhere today. I even have friends now, with college age children, who are afraid of copycat episodes at other universities. They are terrified with their children being away from home and in the university environment. How sad that this is what the world has become.