Anyone know a book on tarot card relationships?

Laura Borealis

I don't think anyone has mentioned Tarot Decoded by Elizabeth Hazel. It's all about correspondences and dignities - elemental, numeric, planetary, zodiacal. She goes into how to use them in spreads with directional scanning. I got bogged down with some of the astrology stuff, personally... but you could easily use just the forms of dignity that make sense to you.