I was recently involved in a CMS evaluation for a rather large client. Their needs were relatively simple but overall they are driven by the lack of a robust web strategy. They have literally dozens of domain names, navigation styles, and even differing content on an entire series of sites spread throughout hosting facilities all over the place. It's a mishmash of things bought and implemented over the past decade or so.
The first suggestion was to bring it all in house. This will allow them to start shutting down hosting accounts, simplify the domain and nameserver management, and allow them to update more easily. This is an ongoing task, not a single step, so keep this in mind.
The next suggestion was to determine what the overall structure would be. You need to know what sort of face you're presenting to the world and determine how the public uses your site. Most of the time you'll want to highlight your products and services, but you also have to put something on your site to convince people to come back. For CaseySoftware, it's our whitepapers and this blog.
The next suggestion was to determine which CMS would be a best fit. They see the value of having a centralized system to manage content across their various sites and have regular updates published. And most CMS's are better than asking the Marketing people to edit raw html.
The final suggestion was to componentize the site. They have a multitude of functionality, information, and tools developed for each of these little sites that are maintained separately and most likely out of sync. Therefore, by moving these components to a centralized toolbox, there can be a single place for all the tools which each page can simply retrieve as necessary.
The formal proposal gets into much more detail with more in-depth suggestions, but this the core revolves around: Simplify, simplify, simplify. Technology is a multiplier on what you can do, not the end solution. Before you launch your site, stop and consider what the point of it is. Are you trying to attract customers? Are you simply trying to have a web presence? Or are you trying to change the world?