It's been a while since I've had a new W.W. Denslow book cover to show! Here we have a Rand McNally paperback printing of A Modern Corsair, by Richard Henry Savage - the man who never learned the proper use of exclamation marks!!
The previous Rand McNally titles that I've shown have all been hardcover books. But Denslow designed quite a few paperbacks for the company as well; many times he did the same title in both paper and hardcover, but the designs don't tend to be the same.
For example, on the right is the hardcover version of A Modern Corsair, courtesy of Cindy Ragni of Avant-Garde Books. A shipwreck is a prominent feature of both the hard and soft covers. This must play into the story, but I haven't read this one yet to know the details! The hardcovers make use of bold, colorful stampings, while the paperbacks feature more linear designs.
For another example, here's the hardcover version of In The Swim, also written by Savage. Bill Thompson recently turned up a paperback version with a very different cover design. The paperback cover is much more of an illustration for the story, which deals in part with shenanigans on Wall Street. On the other hand, the hardcover makes use of one of Denslow's more generic shield designs. However, both incorporate a golden calf, symbolizing the worship of money that becomes the downfall of several characters in the story.