I'd say that it's not really worth it. Spend your money on a UPS instead. The case that your computer is housed in is an important consideration if you plan to add drives to your system or do a lot of work on it. Some major manufacturers have well-designed cases that are easy to open and service, but unfortunately, they're few and far between. They also usually don't hold standard sized components.
Tower cases have two types of covers, wraparound or side panels.
Side panels are typically easier to work with, and some wraparound cases are really cheap and painful to work with. It's designed to sit on the floor and is usually about 2.5 feet tall. The largest towers will have 8 or more exposed drive bays. It's useful if you want the ability to install a lot of internal drives with removable storage capability or if you want to put your drives in removable cases. I even like the exposed bay just so you can have an LED plate attached to additional drives that you can use to easily monitor drive activity.