I had a flight about two weeks after 9/11, and was happy to see a group of burly military fellows on the same flight! Always the crafty one, I carried a mechanical pencil in my shirt pocket, in case I needed to poke some hijacker in the eye...
One takeaway from 9/11 was to increase my situational awareness. Where are the exits? Are there people causing a scene of some sort? I often wondered how many made it out of the towers, but were standing around gawking when the first tower fell on them...
If I feel uneasy, I react. Get the hell out and away. I once ended up in the middle of a bar fight. I noticed the increasing "threat" of trouble; should have hit the door.
As for travel, I have no desire to visit Africa or the Middle East anyway. I'm sure those places are "interesting", but nope... I plan a couple of trips to "Europe", though I'd be just as happy wandering around the countryside as standing in line at a tourist trap. In my weird way of thinking, many of the cathedrals and pyramids and such were built by slaves; I see no need to celebrate that because they're "beautiful".
I don't like crowds, or line-standing, much anyway.
I just completed a week trip to Dale Hollow Lake and the Smokies. No terrorists there, except maybe for the band of yahoos I shared a houseboat with...