I've had a great experience with Apostrophe CMS. It's based on adding a set of plugins to an existing Symfony application, tweaking a few settings, and then saying "I want this part of the page to be managed". Comes complete with roles/permissions ability, and being Symfony, the ability to integrate it into an existing site or extend as you wish.
Very user friendly - log in on the page you want to change, click "Edit" alongside the proposed change, make your change, click "Save", done :-)