Your tour memories can include lunching with a group of Palestinian college students, walking through Moscow with a disgruntled Communist, listening to the Voice of America with curious Bulgarians in a Black Sea coast campground, and learning why the Danes aren't completely comfortable with a unified Europe. Or your travel memories can be built on the blare of your tour guide's bullhorn as he tells you who did the stucco in empty Gothic cathedrals and polished palaces. Certainly we need to consider the real risk of terrorism, evaluate it, and then travel in a way that minimizes the risk. If you can't accept the risk, settle for a lifetime of National Geographic specials. The stealth tourist.
Terrorist targets are predictable.
When you travel through the Back Door, you're melting into Europe, keeping the lowest possible profile. Terrorists don't bomb Pedro's Pension. That's where they sleep. And if you just really hate terrorism, the most effective way for you to fight it is to travel a lot, learn about the world, come home, and help our country fit better into this ever-smaller planet.