Concrete5 is used by universities, museums, governments and large companies all over the world. There's an advanced permissions mode that gives you granular control over who can edit what. The versioning system gives you an audit trail on which users have changed content. Sites with millions of pages in them have been built using concrete5.

Easily change the meta & alt tags on any page. Add your Google analytics tracking from the dashboard without touching a line of code.

Concrete5 is open source, but it wasn't designed by a committee. A small dedicated team of developers manage what actually gets in your concrete5 core with an iron fist. Just like with a Mac, you'll tend to find that things "just work," and there's typically already a easy way to do what you're trying to do if you just poke around or ask.