I have a preference for wanting to sit in an aisle seat on planes, as will always request them when available at the time of booking. Depending on if my upgrade clears, however, I used to be moved to a random first class seat, without regard to seat preference, forcing me to manually go into AA.com or the app upon each upgrade to move my seat to my preferred aisle location.
It’s possible to select your seating preference, so you’re auto-assigned upgraded seat is one in which you prefer, if available.
First, login to AA.com and go to Reservation Preferences.
Then, scroll to the bottom, where you’ll notice your booking preferences.
You’ll see seating preferences as an option, to which you can choose “aisle,” “window,” or “no preference.” Mine is selected as aisle, so when I’m upgraded, if an aisle is available, I’ll be pre-assigned it. It’s worth noting that American tends to assign upgraded seats from the rear moving forward, so if you like to sit in a bulkhead or further forward than the back rows, you may still have to manually go in and select those seats.
For this Chicago to Dallas flight, I was auto-upgraded, but since no seats further back were available, the first aisle seat, on a bulkhead, was assigned.
I’ve had my preferences set in my account for years without much noticeable experiences. It seems like a crap shoot to me.