One key to successfully decorating an open kitchen-living room floor plan is to visually unite the two areas with color. That doesn't mean you have to paint all the walls the same color, but work within one color palette so that you are using colors that complement each other. For example, if you are going for a Tuscan feel, work with earth tones, perhaps painting the kitchen sage green and the living room a burnished gold. Highlight both rooms with accessories that echo those colors as well as some in rich hues for accents that pop.
Floors, cabinets and countertop choices also unite the rooms with color. Keep the same type of floor throughout the space rather than breaking it up with two different coverings. If that isn't possible, be sure both areas have flooring that is close to the same color. Choose kitchen cupboards that complement the living room's window trim and moldings, and be sure you countertop is in the same color palette.
In an open floor plan, your furniture choices should reflect the same style throughout. If you have a rustic country kitchen, don't furnish your living room with sleek, modern pieces. Be sure your furniture looks as good on the back as it does on the front. Because there isn't much wall space in this type of configuration, your couch will often float rather than being pushed against a wall, making all sides visible.
Use furniture pieces to subtly define the space. Set up a conversation area in front of a fireplace, making it the focal point. Arrange stools against a kitchen island or snack bar facing away from the living room. Make use of open bookshelves and folding screens to indicate separate areas.
Encourage the rooms to flow together by using the same architectural elements in both. If the living room ceiling is beamed, include beams in your kitchen design. Paint or stain all moldings and trim work the same color throughout. If the living room has crown molding, mirror that on your kitchen cabinets. Choose windows in the same style in both rooms. If the living room windows are double-hung windows divided into smaller panes, the kitchen windows should be the same. Employ the same tile work on both the fireplace surround and kitchen backsplash