I did and the only one I really didn't consider to be very valid (or at least very low on the totom pole) is the bridge/tunnel scenario. What have the terrorist MOs been? Hitting soft targets where they can cause the most death/injury with the least risk. IF I had accumulated enough explosive to take down a bridge (resulting in low casualities) would I not get more 'bang for my buck' by going after a mall, business center, sporting area (more casualities)? I have yet to see a terror strike on infrastructure except for Iraq, but then the context of that situation is different. Even the rail attacks in Spain were not so much against the infrastructure but to kill people.
I would agree with the understanding that when the number of simultaneous strikes are limited, then it becomes less likely that a bridge or tunnel is a target. But with many strategic targets on the line what would be the impact on our economy if a bridge spanning the Mississippi River could be dropped thus blocking the passage of river traffic in either direction? Think of an attack on the Golden Gate Bridge. Right here in Miami, dropping a bridge (even a small bridge) across the Miami River would put a choke hold on trade with many carribean countries. Don't think of bridges or tunnels with no significance other than traffic convience, think of targets with wide ranging impact if destroyed.