Square dining rooms are problematic because a rectangular or round-to-oval table each with leaves, is the best way to fit various sized groups. 12" is ok widthwise for two 36+" aisles, a 45-48" table and 21-24" for a sideboard. With no other furniture, even 10' works in a squeeze--- but with leaves in a table someone is going to be against the wall or in a doorway.

Squares look nice, and if you have a large square room with an expanding pie-shaped round table ($$$), its functional too--but rectangles seem to give the most flexibility and can be narrow in at least one dimension.

Mine was 13X13 and the most we could fit at our rectangular table was 8. We had a 24" deep buffet in there and it was very tight for the people sitting on that side. I always felt claustrophobic when I was in there(maybe the dark burgundy walls had something to do with it). Anyway, with the kitchen remodel we turned the DR into a study(and painted the walls white...much better!!).

Ours will be 3 sided and 16x11 with a 20 inch buffet on one of the short ends. I am hoping to purchase a 60 inch square table that will seat 6-8 normally and when needed, 2 additional leaves will allow 12.

I have three...one is about 12x11 and we have just the table and a very thin china cabinet in there. It's narrow enough to only allow a table on the side walls and no other serving pieces so I actually cut into the walls and put in another china cabinet that's recessed (the walls were 8" thick). We have served 8 and 9 in there, but we have to turn the table on an angle to do so and it takes coordination to leave the room if you're on the wrong end of the table :)

The other are in a victorian home where dining was an art :) The family dining room is about 15x12 so plenty of room for a family of six if necessary and it leaves room for actual furniture as well.

But the dining room is much larger, about 20x20 on a bit of a goofy angle (fireplace is 45 degrees chopping off a corner, partial bay window follows). There are 5 doors including a door to the outside and very large double doors so furniture placement is sort of precise. But we can seat 14 to 18 pretty easily and then expand to the smoking parlor to sit over 24 without much extra effort. Definately the way to go if you have lots of room :)

in our existing home was to widen the opening between the kitchen and dining...that way when we have larger gatherings we can stretch the table [with leaves and sometimes another table added] between the two rooms. Works great for us.

Here's a picture.

We actually use the dining room now as our eat-in. I love it!

Just last night, I said to hubby, pity we didn't make the dining room 2 feet wider when we built. Our room is 10' x 13'7". Someday, we'll inherit a 48" round table with 2 or 3 leaves. I figured out we'll have 36" between table and wall. Doable. We have a large opening into our living room, similar to what tntw posted above but not wide enough for people to pass diners sitting at the table if we extend the table to full length. They'll have to go through the LR to sit down at the far end of the table.

btw, this DR is bigger than the one in our first house. I think that was only 9' wide and 11' long. It was tight!

Our dining has a wide opening to the living room (12x12) I believe the room is approx 10x12. I have my grandparents dining set in there currently - narrow china cabinet and table that is 38" wide and extends to 96" long. We were able to sit 10 people there for Christmas without a problem.

Here is a link that might be useful: