One of the essentials of keeping your clients websites constantly updated with new content is a blog site. This allows your client with little or no web knowledge to add new content to their blog site by themselves. But if you include a WordPress blog with each static site, what is the best way to maintain them? If you have say 20 different customers, do you really want to maintain 20 different WordPress code bases?
Enter WordPress multi-site. As of version 3.0 you can enable multi-stite from within WordPress as opposed to using a custom module or other modifications. While there reasons both for and against using multi-site discussed on other sites that I researched, for my purposes including a small blog with every site made multi site the best option.