gambler104: You are right about that, but the method I was using lends itself to higher powers of 2 more easily. It also depends on how much importance is placed on the ratings, their accuracy, and the goals of the tournament organizer.

I like to think that the ratings are accurate with the goal to have the best players play each other for the championship and not knock each other out in the early rounds. I'st easy to group the people by adding one to the power of 2 for the number of rounds and then pairing them that way.
8 people is three rounds 2 × 2 × 2 + 1 = 9. 1-8, 2-7, 3-6, and 4-5 should be the first round pairings. If the rounds will not be reseeded each round, which is the normal procedure, the winner of 1-8 should play the winner of 4-5, and the winner of 2-7 plays the winner of 3-6. It's fairly straight forward to draw the tree graph using the numbers and keeping them like that. A few months ago some peole posted some good links for tournament organizers and also discussion various formats of it. Perhaps someone can remember where it is and maybe add the link to this page's title. I'm willing to bet Fencer made a note of it.

For sixteen players you use 17 as the number, thirty-two uses 33.