I like some of the ideas given. When I go out with the family to dinner I always do the same thing.
Sit with my back to the wall and can see the door. I always ask for a table that is not near the front door. I understand I may have to wait. Locate all exits. My family knows to hit the floor and stay there if a BG or anyone draws a gun. Have done this for years.
Second I don't care how you carry if you do not practice drawing from a sitting position you should leave it in the holster. Practice Practice Practice (I dry fire at home and live fire an a local range from sitting, standing, prone, and on my back. Weak hand and strong hand.)