If they don't offer a pre-departure drink, then JUST ASK. If they say no and give some cockamame excuse (other than "no time" when there really is no time), you can "remind" them that you usually get pre-departure drinks in F and ask if there has been some change in policy that AA hasn't communicated to its frequent flyers or something. At the very least, you'll remind the FA that s/he isn't doing their job properly.
I haven't actually done this, but probably will next time!