When planning a dinner party, you may spend a considerable amount of time planning out the guest list, but more often than not while effort goes into arranging who will be at the table, much less thought goes into where they will sit at the table.
Arranging your guests in a way that they are most comfortable and best entertained is key to ensuring that everyone has the best time at your dinner.
The first person which you must consider is your own. As the host, you should be at the seat that is most accessible, as you most likely will be making multiple trips to the kitchen throughout the evening, as well as to the door to welcome newly arriving guests. The host should also sit at the head of the table so that they can best lead the conversation and entertain the crowd.
Though the host may feel inclined to put the person they most want to sit next to alongside them, if there is any guest in attendance who does not know anyone else at the party, it is the right move to seat them next to you to ensure that they have someone to converse with. Additionally, to help that person best settle in, ask them to arrive a little bit early to help you set up and serve, so that you can have some one on one time before the other guests show up, and so that they have an easy excuse to start mingling.
The two most outgoing people at the table should be seated at opposite sides of the table so that there can be an even flow of conversation and entertainment on all sides of the table.
If you have guests coming who may not know each other, but whom you think would get along well and should meet, this is the chance to seat them next to each other!
I also like the idea of mixing people up, and separating people who already know each other. This will keep the conversations more broad and open to including a number of new guests, instead of having a few people sit together who will just spend the evening catching up on things that are only relevant within their own group.
If there are any guests who are coming who have personalities that are certain to clash, it might be a wise idea to keep them seated away from one another.
Lastly, I think it is important to keep in mind that the seating arrangement should not be permanent. A sign of a good dinner party is when people feel comfortable to start moving around and chatting with new people. Your guests, and more importantly you as the host, shouldn't stay in the same place the whole night. This is a chance to mingle with all guests, and to properly enjoy everyone's entertainment.