Order and Reorder

I need to reorder my bookshelf, and I want a system. I am a satisficer and not a maximizer, so no ordering alphabetically or by publishing date - I don't want any system in which there is only one correct place for every book, and sticking it in approximately the right area would mess everything up. I think maybe by country/ geographical region? Either of the author, or of the book's setting. I would rather have, for example, my fiction and non fiction books about Southern Africa sit together on my shelf than all my books by Brits...