In that case (no pre-defined expo layout), print a very large best-guess floorplan of the bar (do reconaissance tomorrow if you can) and create the "seating cha

In that case (no pre-defined expo layout), print a very large best-guess floorplan of the bar (do reconaissance tomorrow if you can) and create the "seating chart" when you get there using pre-printed logos/names of the other companies. Put it on one of those easels. Get there super early so you can get the prime position (at least for a sign of this type) near the primary entrance (assuming you can stake out spots). Arrange business cards like seat assignments. Since you have a mobile Marrily edition, consider building an online version "seating chart" of the ad-hoc expo map as well. If I were going to this, I would find a map useful, especially if all I had to do was go to a short URL.