My only suggestion is to consider making sure you can export the pages wholesale if for some reason you later need to change wiki engines, or change to some other format entirely. Dunno whether or not wikimedia does export. Actually, just easy access to the plain text files (containing the source docs) is what I'd really want (note, some wiki's store that in db tables).

Personally, I'd make sure the wiki allows Markdown markup, and then use that exclusively. It's probably the simplest and most readable markup style, and there's plenty of implementations of it around (Perl, Ruby, PHP,...).