Have you ever seen the Exit rows in an airplane? They longer leg space than coach, and after business or first, they are the best seats in the place. The bad news is that these seats are not reserved for anyone, or at least not in American Airlines. These seats are reserved for those travelers who have some kind of status such as Platinum or Gold. This means that if you do not have a status, you cannot choose them on-line (the seats will show up as unavailable), but fear not - I have found a workaround in some cases.
Say that you have no status at all in American Airlines, but you are traveling with a colleague or friend that does have this status. Before purchasing the ticket, you must tell your travel agent to place both tickets within the same record locator. The person with the high status will be able to select these exit rows for you and you will be able to fly a lot comfortable without having to have a high status.
Be warned that if 2 or more people are on the same American itinerary, and one of them selects an Upgrade to business, everyone in the itinerary will have a request to first. If they do not have enough upgrade stickers, the consequences can be quite bad - such as losing the exit row that was pre-selected and having to fly (if lucky) on the worst seat in the plane :S