It creates elegance and harmony in the space by connecting all the elements into one story when the Persian carpet is the right size. Smaller rugs will make the room appear smaller, while large rugs will make it look larger. Your eye stops where the rug stops.
Generally, a 6'x9' rug fits best in a living room that is 11'x13' or smaller; this leaves about 2' of flooring bordering the rug on each side. If you have attractive flooring but need more comfort, tuck a 6'x9' area rug just up to the nightstands to provide soft cushioning where it matters most. Smaller rugs will be more cost-effective and cover less of your beautiful flooring.