Use furniture to divide the two spaces. Put a buffet, or another large piece of furniture, in the center of the room to break up the two areas. Leave ample space around oversized pieces to avoid making the area feel overcrowded.
Arrange a group of furniture near or on a rug to separate one area from the other.
Paint the rooms in contrasting colors to create a visual separation between the two rooms.
Place a movable divider, such as screen, between the two rooms.
Transition from one area to the other with a pair of columns flanked between the two spaces. Complete the look with decorative millwork for architectural interest.
Build a partial wall to maintain a mostly open feeling while still allowing for some privacy from one room to another.
Install a wine bar with an open serving area and glass shelves to physically separate the two rooms but tie them together with the function of the piece.
Separate the rooms with a double-sided fireplace while adding a touch of warmth and intimacy to both areas.