WordPress as a CMS is a great idea. There is a plugin which allows the use of PHP Includes using [] in place of <>. This opens up all sorts of possibilities.
I currently use WordPress as a CMS for one of my websites, it makes article writing for my staff a lot easier. WP is also so clean and simple, plus it uses CSS layouts and has a lot of SEO options built in, like editing post slugs, the use of H tags, etc...