How do you decide where to sit?

I'm interested in learning more about how everyone here decides where to sit when they go out. I understand there are a few variables to this such as who you're with, how many doors there are, and how many people are in the room. As a student, I have to be prepared for someone coming in the door with a gun (Virginia tech) and someone already in the classroom pulling a gun (UNC). When I go out to restaurants with my friends I have to pick a spot at the table on the outside because I'm not confident in my friend's collective ability to get out of my way. Do you guys try to sit with your back to the wall at the cost of being able to move in any direction? Or do you try and sit closer to a door so that you can handle a threat more easily? I'm not trying to become a mall ninja here I just think this topic is worth discussing as it could help situational awareness. via /r/CCW http://bit.ly/2H6bsae