In my experience, something that already ties into your company's authentication platform can really simplify access-control problems.

For example, when I worked at a company that used Google Apps for Business for everything, I set up our documentation in a Google Sites Wiki. Now that I'm working somewhere that uses Microsoft for everything, I've set up a Sharepoint wiki.

In both cases, the tools wouldn't have been my first choice from a page-editing or layout standpoint, but the ease with which my less-technical co-workers can search and find information and process documents with their existing credentials has been key to encouraging broader use.