I have the book "Interpreting Bach's Well-Tempered Clavier" by Ralph Kirkpatrick which I have found very useful. It is not a one-by-one analysis of each piece but rather a discussion of interpretational principles divided in the three approaches melodic, rhythmic and harmonic.For detailed analyzes of all pieces in WTC you could check out the books by Siglind Bruhn. You can find the content online here:www.edition-gorz.de/bruhn4-engl.htmlOr David Ledbetter's book "Bach's Well-tempered Clavier" which is also very detailed.You should be aware that this is very dense material and while you ask for "something comprehensive", if you are not used to reading such books it can be a bit overwhelming. As an option to get started, have you tried to read wikipedia pages for the pieces you play?You mention Beethoven Sonatas. Read for example:https://en.wikipedia.org/wiki/Piano_Sonata_No._1_(Beethoven)