How you utilize GWS in your particular case depends on the purpose of your Magento installation. With GWS you have an enormous number of configuration possibilities to explore. That said, your configuration planning would generally fall within three major categories: multiple domains, multiple businesses, and multiple languages. Of course, in the real world, a Magento installation may include aspects of all three.
It's important to realize that Magento allows you to drive your e-commerce strategy according to your own business and marketing goals, rather than conforming to any limitations according to what your e-commerce platform may or may not be able to deliver.