Another great option to consider would be Drupal CMS / CMF, where CMF stands for Content Management Framework. Drupal has a huge list on contributed modules that just make your life so much easier. It has better user-roles and permissions architecture than WP. Also the list of SEO related modules that let you tweak everything on your page (titles, urls, etc.) Drupal also provides an editor backend so editors can manage posts and pages. MemCached and Boost will make your drupal site faster and more accessible by search engines as well.
