I remember my dad always having a focal wall even 50 years ago! In a bedroom it is usually the wall your heardboard is on. You can even incorporate your head board into the focal wall. In a living/family room the wall across from your couch is usually the best wall or the one the couch backs up to. If the room is longer you may want to do an end wall. Just remember that a focal wall does not have to jump right out at you. It should draw you into the room! If you have a fireplace that is always the focal wall but in a square room you get to create it.