It is always good to provide the same number of seats in your living room as in your dining room, that way your guests always have a place to sit without rearranging furniture.
Another guideline that I like to work with relates to the living room furniture. I normally use a sofa that is 84” long. It positions people a comfortable distance apart and will fit into most staircases and elevators. ”Most” means you should measure first! It is a good idea to provide a variety of types of seating in a room – some pieces with loose seat cushions for added comfort and some with tight seats for ease when getting up.
I always favor pairs of sofas and pairs of chairs. Over many years it gives you added options for placing your furniture. For me, a love seat and matching sofa is like having a short sleeve and a long sleeve on the same coat. Not a good idea.
-MICHAEL M. MERRILL ASID, NKBA, CID
Michael Merrill Design Blog 