You're rare. (Like me, as it happens; I would judge whether an opening book was worth purchasing by the ratio of text to moves -- the more text, the more likely I was to buy it.) Unfortunately for you, and me, most players would rather be spoon-fed lines to memorize than work on understanding, so that's where the money goes when it comes to opening books. You'll probably need to look in used sites like bookfinder.com for most of what I reference here.
Shaun Talbot's How To Play the Ruy Lopez is the poster-child for what you're after. It splits the Ruy up according to position, and then starts to cover ideas from those positions.
Gligoric wrote a book on the Nimzo-Indian with a smattering of that approach as well, focusing more on a typical position of the opening and plans and variations from there.
Jonathan Rowson wrote Understanding The Grunfeld for Gambit Publications; while it definitely has a lot of explanatory text about positions and plans, it's also more variation-focused than the ones above. Still, you might find what you're looking for there.
I forget which publisher now, but there was one that ran a series of opening books "Mastering xxx with the read and play method" which tended towards that approach as well. It had a stronger emphasis on variations than the previous books, but still covers typical formations and plans.
Bronstein On The King's Indian is another approach: he covers each piece individually, what squares it typically goes to in the KID and what its purpose is in going there. Lots of plans and ideas, almost no variations.
Most of those were never as commercially successful as the ones with variations, so they may be hard to find. A more successful line would be the "Starting Out ..." series from Everyman. They're still heavily focused on variations, but they include typical plans from the resulting positions.
A dark horse in all this might be the two-volume Mastering the Endgame from Shereshevky and Slutsky, wich covers typical endgames arising from some openings and how to play them.
It's hard to begin understanding openings on your own when you're a club player, mainly because you're not sure where/how to start, so you doubt what you build on that. Hopefully, this can get you started out, so you can start building your own understanding without worrying about the foundation.