My foray into graphic arts has given me the opportunity to craft book covers for Brian Schwartz, owner of ePubConversions. I now have dozens of published titles. I also have sample covers. Please visit Photo Innovations blog for additional samples not found on this site.
Many eBooks eventually become printed books, so I always design my covers with that in mind. Full jackets are much easier to produce when creating the front cover, especially if the image wraps to the back cover. Spines are typically flexible since thickness varies with the weight of paper and the number of pages in a book.