What is a wraparound cover? The term itself is self-explanatory—it is simply a cover design that spills over or continues onto the back cover, carrying the same artistic elements. Visionary Jim Steranko is generally credited with creating the wraparound as it applies to comics, using the form for his two-volume Steranko History of Comics. However, it is a relatively recent development in the comics field. It didn't come into common usage until the late 1980s and then was used mainly as a marketing and promotional tool.
As long as you have a concept in mind for the cover, it is really not that much more difficult to design a wraparound cover for the book. Bear in mind that perfect-bound books will have a spine, and the thickness of it will vary based on the page count of your novel and even the type of paper.
This is a technical issue that should be thoroughly discussed with your printer. You will also need to know about proper sizing of the image and bleed areas. This is one reason you should get quotes and line up potential printers early in the project's timeline.
This beautifully designed and rendered wraparound cover for the first issue of The Wild, Wild West comic book from Millennium Publications was painted by Adam Hughes.
Take into account the fact that the design of the wraparound cover will be interrupted by the book's spine, but as long as you're aware of that, it should pose no problem. The wraparound cover gives the cover artist an extra opportunity to shine, plus it gets more information to readers before they even open the book.
The back cover can be all art or graphic elements, or it may contain text, a brief synopsis of the book, or possibly the credits. Since you are already paying for color printing here, you might as well make full use of it and design a cover that will knock their socks off!