Originally Posted by
gateguard0
You can!
Use the free "flight availability" tool on flightstats.com. R will indicate the number of seats available for upgrade, and J will indicate the total number of business class seats available.
Hope this helps you now and in the future.
Thanks for the suggestion! Oddly, it shows R1 and J1 right now -- maybe it doesn't have instant updates, and my mother in law actually grabbed that last seat?