In Italy, there's an unwritten code for what pasta goes with what types of sauce. Like language, the best method of learning this pasta culture is immersion. Only because the rules seem a little arbitrary and silly if you just read about them. But if you can taste the difference, and you can see the way certain sauce clings to different shapes, then pairing garlic and oil with a light angel hair, but pairing alfredo with thicker noodles like fettucini makes perfect sense. (It also helps to have a host mom that just shakes her head in disgust at your untrained suggestions...)
Usually I just go from memory of what my host mom did, but Chow has this great cheat sheet!
And while we're on the subject of pasta, if you've been tempted to make your own, here is a video to help.