I can recommend "Classical Music - The 50 Greatest Composers and Their 1,000 Greatest Works" by Phil Goulding, 1992.
Best single volume guide to classical music
For a Valentine’s Day present. Preferably fun to read. Doesn’t need to get deep into minuscia. At this point in our evolution, I could imagine one with QR codes to take the reader to great performances of pieces. Or a downloadable supplement! But I doubt that exists. Anyhow - thanks in advance.