I've noticed that a lot of girls say their favorite position is Doggy. It's mine too, but just for fun I was wondering why the gals preferred it. Please add to my first three thoughts...
1). Its more sexually satisfying. You get more depth, or hit the G-Spot better, the angle works best, etc.
2). Its easy - lots less energy than Cowgirl, for example. You're in a pretty comfortable position (some don't even move). Over the whole day, you're less tired.
3) You don't even have to see or smell us. It could be Chris Pine humping ya...