Edited Down to Simple Substance
So how about a more germane question? “Given the types of incidents that have been taking place and those that have been historically typical in Europe, what can I do to minimize my exposure?” First, when you build lists like this it sort overwhelms the senses. I am not encouraging anything, or anything to one degree or another, but things you yourself might want to take into consideration and weigh vs your own thresholds of comfort are:
Generally, the areas most tourists visit are as safe as the suburban neighborhoods those with the disposal income to travel live and work in.
While the mass shootings in Paris have resulted in 6 times the number of per capita causalities than have resulted from mass shootings in the US, by definition it only takes one MASS shooting to flip that comparison, so when it comes to things of this magnitude it’s not always relevant to play the number games.
Jews are targets of right wing and Islamic extremists. Being in the proximity of Jews or Jewish monuments is going to be more dangerous than being in the proximity of Baptists.
The immigrants are targets of right wing extremists. Being in the proximity of immigrants is going to be more dangerous than being in the proximity of Baptists.
The immigrants generally speaking were not raised in the presence of traditional Western values and some among the immigrants may act out on the differences in culture. In the presence of immigrants, people may want to consider how they are being perceived by the immigrants; this is apparently especially women.
In many crowded tourist zones pickpocketing and petty theft is fairly prevalent.
“Wandering neighborhoods” may best done in day time to avoid ending up in the “wrong” neighborhood; especially after dark. Demographics are changing and what may have been okay when your 1997 RS Guide was written may no longer be true.
Breaking laws, no matter how small, may bring you into a legal system that does not provide the same protections as the US legal system.
As the crime rate in most of the EU is fairly uniform, you might look for places where the terrorism risk is lower. As mentioned that would be Eastern and Central Europe.
Read the US State Department advisories and I like the ones the UK publishes too. What harm could it do? Also you might want to register with the State Department STEP program.
The population in some countries is less tolerant of U.S. foreign policy and responds through protest and violence in the streets or rudeness to tourists. Be aware of how the U.S. is being perceived during your visit. I’ve never heard of a violent outbreak because of Russia’s aggression against Georgia or the Ukraine so I assume that this is very U.S. biased.
The population of some countries might be more prone to respond to dissatisfaction with their own government’s policies through protest and violence. Have an awareness of any local topics of discord.