If you have one formal and one casual dining space, you can really go to town with different chair designs for both. A casual spot will do best with sociable, comfy seating that naturally leads to conversation, whereas a formal setting is where you can play around with luxury fabrics. If you only have one dining room, you're going to need to combine all of these elements in one set of chairs, if possible!
Dark wall, with dark wood furniture illuminated with warm lighting does not make the space seem narrow, as one would imagine, rather it makes the whole area appear quite warm and cozy. The black chairs complement the black wall, and the bench is definitely the center of attraction of this open dining space.