They are my favourite covers too: as you say it is the accurate detail which pleases, as well as the pictures themselves. (Though with respect to much loved books, I also always find that I have certain tendresse for the cover of the first copy I read, even if other versions are more aesthetically pleasing.)

My original copy of Peter's Room was one of Faber ones - and the top half was a Gondal scene; and I liked that bit too (though it had the same weird, unidentifiable faces below). Alas, the book has vanished so I am left with my dust-jacket-less ex-library hardback, saddibus.