If you still haven’t scored your ideal seats, it never hurts to ask about upgrades or last-minute cancellations as you are boarding. Upgrades are generally reserved for elite passengers and frequent flyers but it can’t hurt to try! And remember that you always catch more flies with honey than vinegar so be extra friendly to the flight staff.
Finally, if you aren’t afraid of possibly stirring up a little trouble, consider investing in the Knee Defender. It’s an inexpensive device that attaches to the seat in front of you and prevents the occupant from reclining.