I completely agree about a book with more practical applications of Tarot -- Tarot in our everyday lives. Yes. And a book about readings that were tricky. Also, what about the querent's experience post-reading? How did the cards help? Hinder even? What happened? What was the outcome? If the interpretation wasn't on point, what other insights came into play? Maybe bringing readings out of the "sterile" reading environment and into the day to day world, the idea that a reading doesn't stop at the end of the session. We never seem to get to read or hear about what comes afterwards.
I'd also love an informational book in an everyday, friendly style that gives a well-researched account of the Tarot tradition, particularly in relationship to Rider-Waite and Crowley, how those two major decks are similar, how they are different, and where the influences that shaped them both intersect and disperse. How has Tarot changed over the decades? Where are we now? What kinds of trends are on the horizon?
Good luck with whatever projects you pursue, Mark!!