When deciding on the right size sofa to bring into your living room, there are several things to consider. First, there are matters of numbers. How much physical space is there in your room for a piece of furniture?
Then, some factors vary significantly by family and individual. How much seating does the space need to have? Do you have three kids, live alone, or have a significant other? Or, how often do guests come over? Answering these questions will help you determine the basic size couches to browse.
For example, if you determine it's mostly you and one other person, a small three-seater may be the best choice. If you find that you'll need 5+ seats frequently, a larger sectional may be the way to go.