I build all my sites now on the Open Source, Drupal CMS (Content Management System). Drupal is an extremely powerful and flexible platform, capable of creating large enterprise sites, as well as simpler, blog-style sites. The beauty of the platform is that it can incorporate custom content types, specifically tailored to your needs. And a well-built site is very simple to use and manage, so you can be in complete control of your content.
And if you need specific functionality for your site, there are thousands of modules available to extend and amplify the core Drupal installation. The saying in the Drupal community is "there's a module for that." So just about anything is possible. And with Drupal's extensibilityyou can start small and always grow from there.
Dries Buytaert, the original developer of Drupal has an excellent collection of samples of sites built with Drupal on his blog—including WhiteHouse.gov, and more sites of every size and kind. I recommend browsing through his collection, just to get some ideas of what's possible, and for inspiration in designs and structure.
I have years of experience building websites. Call me at (603) 478-4234 to discuss your project.