Jackson Airport has an observation pier in the center of the airline terminal complex. Unfortunately, after 9/11 it was closed because people might go look at planes. I've asked before and the powers who be in Jackson say that there are no plans to reopen the observation pier. Shame.
You might want to consider shooting from the east end of the passenger drop/off lanes. The road that leads to the drop off area goes up a ramp and turns west alongside the terminal. The view of the east runway and ramp area right there is decent as it's elevated. However, you might be met by some resistance from law enforcement. "Looking at planes is wrong after 9/11 ya know"
International Drive leading into the airport has a nice view of 34L. If north ops are in progress, this would be a nice place to get arrivals in the morning. Airport Road to the west of the field seems to have a good vantage of ops in either direction in the afternoon.
Keep in mind, JAN is crawling with feds. A local FSDO office is located just south of the pax terminal along International Drive. Also, an ANG base is located on the Northeast side of the airport, so, wise to stay far far away from there.
It'll probably be a good idea to call the AIRPORT POLICE ahead of your visit and state your intentions. This approach usually yields positive results more than negative. And if they tell you to piss off, there are a number of GA
airports around Jackson that would be worth scoping out.
Forgot to add: If you've got time and cash to burn, a (3 hour drive each way) road trip to Tupelo, MS to check out the airliner boneyard/scarpping they do there might be of interest. I've always wanted to scope out that place.
[Edited 2013-05-11 10:54:59]