Well, I'll be following your mission with interest, then -- I've read "Prime of Miss Brodie" (of course) and her bio of Emily Bronte, and I actually own the two-volume hardcover edition of her collected novels, so I'm definitely planning to read more of her fiction, too ... maybe one or two of her works will fit into next year's reading.
http://www.usherhall.co.uk/whats-on/muriel-spark-crème-de-la-crème
Next up: Memento Mori, then the satires, then the short stories.