There's a brief article at a site called "The Older Gamers Paradise" about The Rise and Fall of Sega. It's not so much a detailed factual history as an opportunity to reminisce with a former diehard Sega fanboy (who now sounds a bit jaded, if you ask me). He's got some interesting speculations Sega's most fateful mistakes, the biggest seeming to be creating massive consumer confusion around 32x and Saturn. Here's an interesting thought--If Sega had used the CD unit as a springboard until perfecting the Saturn, things might have gone differently. If you're a Sega fan (or just want to see what the nostalgia is like from someone who is), you'll enjoy reading the article.
*sigh* After reading this incorrect statement, "Initially the Sega CD and 32X were supposed to be compatible, but that fell through.", I stopped reading (oh OK, I kept reading, but frankly I found the editorializing way, way off base). It's funny how I have 32X CD games sitting in my room that work perfectly fine. I guess myself and thousands of others are just "lucky". It is quite a monstrosity though when you have a Genesis, Sega CD and 32X all hooked up at the same time, all with large individual power bricks and all daisy chained in an insane way. It's a miracle it does all work, but work it does.