"Less is more in transitional spaces or entrances that open to other rooms or a stairway," says Mahmud Jafri of Dover Rug & Home in Massachusetts: "But the width should either match the door space or be a few inches less — not too long, not too short." If you use a round area rug in a large foyer, center it under the light fixture. In a hallway, stretch the length to fill the space, leaving even space on both ends for balance. And if you plan to place any furniture in the hallway, keep it off the rug. "No half off, half on there," he says.

For the home office, perhaps in the corner of a bedroom, "Treat it like a cocoon," Mahmud says. Choose a rug that completely fits both the desk and chair to create a warm space where you'll feel comfortable at work. For practical purposes, this prevents tripping or chair dragging over the edges of the carpet, which are the weakest part of the accessory, he says.