Commuting to work on a busy highway, I have found that obeying the rules of the road and staying in the left lane, unless overtaking, results in a smoother, more comfortable, and safer drive than driving in the right-lane. I also doubt that I am significantly slowed down by driving in the left lane during peak hours.
I hate drivers who, for no reason, decide to hog the right lane and disrupt the smooth flow of traffic. Unless I am mistaken, there is no penalty for hogging the fast lane. Perhaps the authorities should introduce fines for right-lane hogs.