I agree that terrorists want us to be afraid, that is why it is called terrorism.
My own personal take on this is that places there there already have been attacks are probably less likely to be attacked again. They step up their security after an attack and I believe the terrorists are more likely to attack new places to increase their effect. So I would be less afraid of going to places that already have been hit. Plus there is no way to predict who will be attacked next, so why not go anywhere. Or course this doesn't not mean going places where there is active conflict, including drug wars.
Of course I don't know this for sure, it is just my guess.