Problem: Relying only on last modifiers, page creators, and space admins to touch/review pages isn't enough. Some of these people have left the company. Additionally, some people filter mail sent by the wiki, consider it spam, and never read it.
Solution: Post a custom banner in a specific wiki space X weeks before it gets archived. The banner would include a Page Tree link to the list of expired candidate pages (for example, https://iwww.acme.com/wiki/cf/archiving/events.action?key=VCIO&type=*#). Using this banner, anyone viewing the wiki space can touch a page (assuming they have edit access) before it gets archived. The bottleneck of only last modifiers, page owners, and space admins is removed and checking email is not the only form of notification.
One more thing ... to the banner, add a page view counter. It tracks the total number of views of the banner itself and number of clicks on Page Tree List since the banner was posted. When the banner is taken down, the counter resets to zero (or gets saved to a historical store).