Table numbers

I agree with pp. Even with a "small" group of people who know each other, they are not going to efficiently seat themselves into groups of 8 or however many your table size requires. It truly is MUCH better that you figure out which table to seat people at and let them know the expectation with a table chart or escort cards. Without assigned seating, some venues actually require the customer to plan for up to 25% more space/seats/placesettings/etc., because people will do weird things.