House Design - Traffic Patterns
Figure out the most efficient people paths within the house.
Site lines are primarily concerned with static views. Traffic patterns help you understand how your house will perform dynamically. Traffic lines help you understand how people will move around the house in their daily life. Traffic patterns answer questions such as - How will food get from the kitchen to the dining room? How far does a mother need to walk from the master bedroom to check on the baby in the other bedroom? You need to make common activities as friction-free as possible. If you always have to walk the long way round a kitchen island it may start to really bug you. If the only way to get from the front door lobby area to the formal room for meeting with visitors is via the messy family room then that would be a mistake.
Modern floor plans tend to avoid using hallways and corridors to get from one place to another. This is because they tend to be regarded as wasted space. Nowadays designers tend to use other rooms as ways of getting around, but it's necessary to think carefully about whether this traffic through the connecting rooms is a problem. If your teenage son is entertaining his girlfriend in the room then he is not going to be too happy about the rest of the family walking through to get to the family living room. Using small rooms as connecting rooms does however make those small rooms seem bigger as it opens up site lines. If you are using rooms as passageways, try to put the traffic along one wall rather than making the path diagonal across the room. This design technique is called "horizontal banding". Personally I think hallways do still have a place in today's house plans, but you do need to use them sparingly and not make them too long or narrow.
Consider where people will naturally hang out the most. As the song says "You'll always find me in the kitchen at parties". Kitchens are often the hub of a modern house. This contrasts with houses from 100 years ago were the kitchen was small and hidden out back somewhere. A modern kitchen should be large and in the center of the house, and it should have lots of entry doors so that it's easy to get (and see) from the kitchen to any other room.
If your house is 2 story then you need to have stairs up to the bedroom level. If you have a basement then you need to have stairs from the basement. Stairs take up lots of space, so if you have a basement then you probably will need to put the basement stairs under the bedroom stairs to save space. Some people like to make a feature of the stairs and make them look grand, and some people like to make them as small as possible and hide them. Personally I prefer the featuring them approach. I like them to come from the lobby area as they help with the grandeur of the lobby and make the lobby area less closed in. You can see upwards from the lobby as your eye follows the line of the stairs. When designing a layout, it is important to reference all the building code requirements of stairs (see here ).