I like QuiltE's suggestion. The FQ on each table and then as a door prize is a good idea. How many tables do you need to decorate? The table cloth that comes on a roll would be a good idea. How big is your budget? I do think you should cover the tables. Having everyone bring an ornament is a good idea, maybe to exchange since people tend to take the center-pieces. Do you have a christmas tree farm near you? You can usually get cuttings from them free.
Sue