How to seat wedding guests
How to work out who sits with whom when your groups don't divide neatly into tables: what has to hold, what can bend, and how to read the whole room before you commit.
Start from how people know each other
It helps to note the relationships before you place anyone: which side of the family someone is on, which friend group they belong to, whether they are coming with a partner or on their own. Deciding who sits with whom depends on all of that, and a plain list of names records none of it. A short note beside each guest, or a handful of named groups, is usually enough to work from.
Separate the fixed points from the preferences
Some things you will probably treat as fixed: a couple sits together, two people are kept apart, a guest who won't know many people is seated near someone welcoming. Others are closer to preferences, worth having but able to give way when space runs short. Marking which is which early is useful, because once the tables are nearly full you will want to know what can move. Where you draw that line is your call; another host might treat the same request as optional.
Groups rarely match the table sizes
If every group were exactly the size of a table, there would be little to work out. In practice a friend group might be nine while the tables seat eight, one guest belongs to two circles, and a couple straddles both families. These are the points where you actually have to choose something, and they are usually where your attention is best spent rather than on the tables that fall into place on their own.
Splitting a group that is too big
When a group will not fit on one table, someone sits elsewhere. A reasonable starting point is to move whoever has the loosest tie to the rest, and to seat them at a table where they already know at least one person rather than wherever a seat is free. It is not a firm rule. Sometimes it is a pair of friends happy to move together, or the guest who would rather meet new people. The aim is usually the smallest loss to the people involved.
Anchoring each table
A table often works best when it is built around a person or a pair who hold it together, with the others connected to them in some way. The tables that tend to struggle are the ones assembled from whoever was left at the end. If a table is starting to look like a collection of odd ones out, it is usually the first one worth revisiting. Our note on how to avoid the leftovers table goes into this further.
Look at the plan as a whole
A table can read well on its own and still not suit the room around it. Moving one guest to improve a table changes the people on either side of them, so it helps to look at the arrangement as a whole once the seats are filled rather than judging each table in isolation. You are looking for a plan that hangs together, not one where every table happens to look fine on its own.
A strong arrangement can still be wrong for your guests
An arrangement can meet every requirement you set and still not feel right. Often that is a sign of something you know about your guests that never made it into the plan: an old history, a quiet friendship, a person who would simply rather be elsewhere. It is reasonable to override the plan in those cases. The requirements handle the bulk of the work; they do not have the final say over your own judgement.
Where Lennea fits
The reasoning above is manageable by hand for a few tables. It gets harder as the question turns into who goes where across every table at once, with all the couples, groups and people to keep apart holding at the same time. That combinatorial part is what an optimiser is good at, and it is what Lennea's wedding seating planner does: it produces a first arrangement from your groups and constraints for you to review, adjust or set aside.