As a survivor of 4 of those BOS3X trips on flight 192 I'd say....UPGRADE if you can. Any way you can. Stickers, Miles+Cash, those flights were so bad I'd even consider using a SWU.
Then again, I've sworn I will never, ever, fly flight 192 again.
The BOS3X AA192s on Friday nights were just absolutely packed. If EF shows anything less than 7 for the coach tickets buckets, I'd be begging for any form of upgrade.
Hyperbole aside, ask for the upgrade - the 757 coach seats suck.
Jim