The guy has a very neo-classical style, which is a very safe conservative style. However, I think his designs could be stronger. He seems to struggle with emphasis. Though he has a good grasp of chiaroscuro, I'm not seeing him use it to articulate any motion in his works. In other words, poor concepts, but great technique.
Course, for your first book, picking a conservitive/technichy accomplished artist is usually a good idea. Course, I think I prefer more avante garde covers since they stick out in my mind more and help the book be distinguished from other books on the shelf. I also hope you get some good typography done on your cover. Those covers had a lot of just tacky typography.
Also to answer your question reguarding James Christensen, no he does not create works specifically for cover art. At least last time I spoke with him, which was at his exhibit opening last september(?). Course, if you find a work of his that matches your book he will usually consider you letting publish it.