A guaranteed seat to every game plus playoffs....the same seat every game. Oh, and a nice logo cap with "Season Ticket Holder" with your section on the back....
Besides the obvious (guaranteed entry to every home game at face value without going nuts and paying a premium), you can also get premium parking and entry to the Stadium Club downstairs. As mentioned, if the Jets get into the playoffs, you get first right of refusal on the playoff tickets, again at face value, which would probably be considerable less than what street value is. If the Jets make it to the Superbowl, there's also a formula for this for ticketholders. From memory (and someone correct me if I'm wrong), 20% of all the Superbowl tickets are reserved for season ticketholders of one of the teams involved. In other words, if the Jets are playing the Giants in Miami, 20% of the tickets would go to Jets seaon ticketholders and another 20% would go to Giants holders. That's 40%. The remaining 60% is broken down into 20% for NFL employees and others and the the last 40% gets sold to the public ona first-come, first-served basis. A lottery is formed by the Jets FO in which all the Jets season ticketholders are in contention to receive the 20% Jets alottment. So, you have a shot at getting Superbowl tickets at face value, again, considerably below street value. But generally, season ticketholders get to enjoy the games better, I think, than somebody who is constantly foraging for tickets. You know where your seat is for every game, so you get into a routine as far as where you park, which gate you use, who your tailgating "neighbors" are, and you get into a routine as far as what time to leave the house to avoid traffic at your particular entrance, etc. It's just nice to know you have a seat and don't have to worry about dealing for one, so you can concentrate on "serious" tailgating.
But we will have won our second, third, and fourth Superbowls by then, so I'll have to charge you a premium! Oh... Hope springs eternal....