With two kids and two dogs I use the stretch slipcovers made by Surefit to protect my sofa and oversized chair.  I usually have to buy new ones at least once a year so I purchase them from  Overstock.com - they are much cheaper, than buying from the Surefit website and shipping on Overstock.com is only $2.95 for all items and they have a great selection of the Surefit brand.