My sister in Baton Rouge has a "whole-house" generator. Several years ago she lost power during a hurricane and was out over two weeks...she had to drive to Liberty, MS to get gas to run her small generator that kept her refrigerator and freezers running (not to mention the work of keeping it filled). Following that episode, they had the standby generator installed. It ran for 88 hours during and following Issac. She thinks it's worth every penny. If you live in Louisiana, you can be sure there will be another hurricane.
We had a Generac installed last year because if we have an ice/snow storm and lose power, we can't get out and depend on electricity for everything, even water. It has run a few times for several hours...we just consider it insurance.