Thoughts;
Sit in a position that allows you to see the most you can of the dining area and the entrance to the dining area.
If I have to chose, I'll take the view of the entrance to the dining area over being able to see all the diners. I figure most are there to eat and few robbers have the nerve to dine & rob.
Tables are better than booths - more directions for you to move and you don't have to "slide out". Additionally, some booth seats are awfully soft making it harder to get out.
In a booth, gun-side out means you can engage from a seated position while pushing out of the booth with the off hand.
In a booth, gun-side in means you can covertly unholster and slide hand and gun under the table. Use your off hand to pull yourself out of the booth using the end of the table.
Gun-side out means you can fire further down an aisle without crossing patrons at your table or others.
A table can be flipped on its side for concealment/cover where the table in a booth generally cannot.
The almost ideal position is a table towards the back of the dining area, with a wall behind you, windows overlooking the entrance walkway visible, and where "customers" at the register will have their back to you.
I spend more time worrying about the quality of their cooks and their food than I do that some kind of robbery will go down.
In any place that might be robbed due to its location, the parking lot is two to three times more dangerous than inside the restaurant.
A robbery in the parking lot increases your danger level 1000%.
In a parking lot robbery, the thief expects the male to be the one likely to resist/retaliate/attack. So fellas, get your wives CCW's and distract while she shoots!
That's my thinking on this subject.