I’m frequently asked what control I have over cover art. The short answer is, all I want. There’s nothing about cover control written into my contracts, but I’m on terms of friendship with both my publishers. If I said, ‘I want Smith to paint the cover, and this is the scene I want him to illustrate,’ that’s what I’d get.
I never do that, and I think that writers who do are being foolish. (Unless there are other factors: I know of cases where writer and artist were in a relationship, in which case the writer got benefits which perhaps counterbalanced the cost to the book.)
I’m neither an artist nor an art director. Even if the artist and art director were bad at their jobs, they’d still be better at their jobs than I would be at their jobs.