Places on the Edge
People tend to gravitate toward the edges of a space rather than in the middle because the edge offers psychological comfort in the sense of a feeling of protection. Places on the edge also allow a person or a small group of people to be separate from everyone else, yet still connected. This is because a place on the edge is still within sight and sound of everyone else, and not particularly far away. If you don't provide one, people will tend to move to the edge as long as there is a place there to move to. In fact, if you look at rooms, you'll see that almost all furniture is always on the edge (the common exception is the dining room table).
Places on the edge are the places away from the flow that are made for sitting or congregating. Most people will prefer to sit near an edge than in the center because it gives a feeling of protection, while still allowing a feeling of connection. If the place on the edge is near a window, it allows a connection to both inside and outside at once. Almost every room can incorporate a place on the edge, although not every one needs one. Some of these places should be sunny places, and others should have only indirect light. If you find yourself sitting at the dining table or in bed reading because there is no place else to go, then its likely that you don't have enough places on the edge. This pattern applies to outdoor space as well.
These places could be created just by placing furniture along a wall, or a special alcove could be built for them. Sunny places are often the most cherished spots in a house during all but the hottest days of the year.
Here are some examples of places on the edge:
Window seat - most everyone loves a well made window seat. A window seat needs to be wide enough to sit on it comfortably and long enough to be able to put your legs up on it. If the intent is to ever actually sit on it like a chair, then it can be no more than 18" off the floor, but in our experience few people sit on them that way. The back needs to be sloped, but you can do that with large pillows if you don't want to build a sloped back. If the window seat is the size of a single bed, you can put a futon mattress or the equivalent on it so it can double as such. While window seats are often in living rooms, you can put one in a reading room, and office or even a hallway.
Breakfast nook - these are also well loved spaces, especially when the face east to catch the morning sun. They should be big enough to fit 2-4 people, but not so big as to lose their cozy feel. Its after all a nook, not a room.
Heat source - people like to sit around the fire, and preferably look at the flames or at least be able to feel the heat radiation. While tight houses necessitates closed combustion devices, there are still stoves that you can see the flame thru a sheet of glass.
View - people will gather around a view the way they gather around a fire, so view places make great places on the edge.
Sitting circle - people engaged in conversation like to be arranged in a circle or semi-circle, so arrange a living room around that.