Darren,

I am not sure what industry you are in but I would suggest localizing the content.  This will help you avoid duplicate content  while providing a richer user experience and some local SEO juice. So I would incorporate references to local landmarks as well as anything in the area that affects how the category might be implemented. So for example a page about tomatoes in southern California might focus on fertilization to maximize production while a similar page in Anchorage Alaska might focus on how to grow tomatoes indoors hydroponically.  This is an extreme example but I thought this might give you the idea.  You want at least 65% on the content to be original even though it might talk about the same things.

Ron