1. Avoid spacing round tables widely apart in an attempt to fill the available space. Distance makes audience involvement and participation much more difficult. A better idea would be to space the tables as close together as practicable (allowing enough room for comfortable waiter and waitress movement). Empty room space could be filled with a decorative divider of some sort.
2. Avoid a great distance between the head table/dais/speaker area and the first row of tables. Again, distance is a great barrier to speaking and interaction.
3. Try to set the head table / speaker area on the long side of the room. This means that the back row participants will be closer to the speaker than if you set the head table / speaker area on the short side of the room (participants will feel they are really far from the action).
4. Consider allowing the speaker an option of speaking areas. Many top speakers can do a better job if they are not confined behind a head table and/or lectern while speaking in public. Most public audiences like being closer to the speaker too. To accomplish this, place extra chairs near the front of the room to be used by the head table participants after dinner (of course, this would depend on your overall program). You would not want them seated behind the speaker during the program. Set head table back from the front of the podium. Speaker can perform in front of the head table.
5. Set buffet tables far to the side or on the opposite end from the speaker area. If someone goes back for late seconds or arrives late, he or she will not be disruptive.
6. Discourage use of doors anywhere near the head table/speaker area.

TIMING

1. When speaking in public on a tight time schedule, have desserts placed on the table midway through the meal.
2. Arrange with banquet staff to cease all bussing of tables on a pre-arranged signal. Many functions have less than interesting openings because service personnel are running around for the first 10 minutes of a talk. This gets everything off to a bad start.
3. Ten minutes before the program is to start, it is very helpful to announce something like the following: "The program will start in ten minutes. Please get your drink refills, (go to the little boys and little girls room), grab another piece of cake and then take your seats and get ready for a great program!"
4. When planning lighthearted / humorous speaking programs, avoid heavy subjects before the speaker, i.e., don't show tearjerker slides of starving children (actually happened to a speaker friend of mine), in an effort to raise funds. Don't get me wrong, I'm all for raising funds for good causes, but if you do this just before a humorous public speaking event or comedy show, you may have wasted your money on the talent and actually made it inappropriate for them to do the job for which they were hired.

When speaking in public at settings where food is involved you must make a special effort to take care of logistical details so your speech is well received.