I would say the most frustrating part about the planning process for the couple, is assigning seats at dinner. No one can help you with this, because no one knows every guest the way you do. This being said, I would like to TRY to help by giving you 5 little tips:
1. People LIKE to be told what to do and where to sit: So many of my couples think they are being more courteous by not assigning seats and allowing people to sit where they like. Not true! If you don't tell them where to sit or what to do, they get a little flustered and look to your wedding planner, serving staff, etc. to guide them to an appropriate seat. Assigning seats actually reduces anxiety for many of your guests.
2. The exception to number one is there are a few people that HATE being told what to do. These people will change seats, move placecards, etc. Accept that your perfectly designed seating chart will be changed up by that one person who interprets your seating assignment like the authority he has long, deep rooted issues with.
3. You will NEVER make everyone happy. Don't even try. Try as hard as you can to make most people comfortable, but know that someone on the list just won't fit appropriately at any table. So, don't beat yourself up. Just except it and for heaven's sake, do not show anyone not within the immediate planning committee the seating chart in advance. Unless you like hearing things, like "Why do I have to sit next to Aunt Susie?" or, "I can't believe you sat Allison and Esther together. They are going to bicker all night." Guard the chart with your life!
4. People cancel, people show up without RSVPing and dates change. Be prepared by having a few extra seats and/or place cards on hand to ensure the unexpected guests do not feel uncomfortable.
5. If you don't assign seats some guests will be out in the cold. Have you ever been that guest at a wedding sitting by yourself or with one or two other random people in the corner? If so, I would venture to guess they didn't assign a seat for you at dinner. If you don't assign seats, families of four have to split into multiple tables because there aren't four seats left ANYWHERE in the place and guests coming in late from the cocktail hour end up in no man's land at a table with people they don't know or don't care to know.
Take my advice on this one little thing...assign seats, but don't be so bought into your assignments that you will shed tears if someone shows up unannounced or the grumpy old man that was your neighbor ten year ago bucks your suggestions and decides to cram into one of the other tables. It does and will happen, but try to make a MAJORITY of your guest comfortable by giving the seating chart some thought and then be sure to let it go!