I have been prototyping some changes to account for feedback. At this point I can't make promises that everything below will be in the release, but there is a good chance that it or something like it will be there.
First, cover size and aspect ratio. There are the four choices mentioned above. Here are screen shots for square w/aspect ratio, square w/no aspect ratio, portrait (7/10) w/aspect ratio, and portrait w/no aspect ratio. Note that one cover is in landscape, and shows the differences most starkly.
Here are the shelf colors/materials I am playing with. First the colored woods, light, medium, and dark. The center image, medium wood, is what is there today.
And the grey woods, light, medium, and dark:
