One of the first things you will have to ask yourself is where you will be placing your dining table. A round table curiously seems to draw all elements that surround it towards it, thereby anchoring itself (and the chairs) visually more than a rectangular table would. It also takes up less space.
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.