My personal wiki is a study and reference tool, so it's structured by subject/vendor (Microsoft -> System Center -> Operations Manager)
My version of the work wiki is structured by customer, then drill down to different sections and eventually individual pages (CustomerA -> Servers/Devices -> ServerA). Unfortunately this project was shutdown as we were ready to go into testing, so I have no idea how well it works in a production environment.
If I may, I recommend looking into Tiki Wiki. It's FLOSS and relatively easy to figure out if you like reading documentation. The Structured Wiki would be your primary feature. For making sure people see changes, you could use the Newsletter feature for distributing changes by email. Or, if you want to be more passive about it, you could create a tracker for important changes then put a widget on the home page of the Wiki displaying the most recent item(s) submitted to the tracker. Or you could do both, saving newsletters to a tracker and then publishing that tracker to the wiki home page.
You mean a ready to go package supporting all this that you can host yourself? Sounds like you're looking for something like a Content Management System. There are bunch out there, but they will require a good level of customizing.
Tiki Wiki is my go to CMS. It could do what you're looking for, but it does require a decent amount of time to learn about the features you'll need. If you have a budget for this, you could find a third party consultant to build it for you. There are a number of companies globally who specialize in Tiki.