Keep in mind that the seating arrangement should serve two purposes: to allow all the guests the pleasure of the hosts' company and to make the party as enjoyable and interesting as possible.
According to traditional guidelines, the host and hostess should occupy the two seats at either end of a table. Singles can be seated where you like, and couples should be split up so they have a chance to socialize with other people. Each seat should alternate genders, and if there is to be an unequal number of men and women, space them as evenly as possible around the table.
The seats to the right of the host and the hostess are considered positions of honor. If there are any guests to laud, the man of honor should sit to the right of the hostess, and the female guest of honor to the right of the host. Think about which guests might have a good time sitting near one another. You might put two film buffs together or a shy guest next to an outgoing one.
Before your holiday gatherings begin, relocate your coats from the hall closet to a less central one so that guests will have a place to hang theirs, rather than piling them atop a bed. Be sure to have ample hangers, plus a basket for gloves and hats.
Also, clear out the refrigerator if guests will be bringing beer, Champagne, or foods that should be chilled. You may need to relinquish oven time to a relative's side dish, so plan your cooking schedule accordingly.