You want all of your wedding guests to have a fun time at the reception, and part of that is planning seating arrangements that work for everyone. Though the choice is ultimately up to you, there are certain conventions most people follow when planning who sits where. If you prefer tradition, there are some rules to keep in mind.
According to Martha Stewart Weddings, the bride and groom should be seated in a central location, so that all guests can see them. Sometimes the bride and groom will have their own "sweetheart" table, but often they share a table with the wedding party. If seated with the wedding party, the best man should sit next to the bride and the attendant of honor should sit next to the groom, with others fanning out in a male-female pattern.
At the hosts' table, the mother of the bride should sit facing the guests, so she can monitor how the party is going. The father of the bride, the groom's parents and the officiant and his or her spouse will also sit at this table, alternating in a male-female pattern. Same-sex couples should sit next to each other despite the traditional rule of alternating men and women.
Basic etiquette works for those with traditional families, but if your family is not so traditional, you may have to make special arrangements. For example, if the parents of the bride or groom have divorced and remarried, you may want to seat those couples apart from each other. This might mean setting up two tables of equal importance near the bride and groom's table.