They used to let you do this in the National Guard believe it back in the early 1980's or maybe I was just priveleged.
I got about an hour up front, in a Missouri Air National Guard C-130. I was standing the whole time and I was like a kid in a candy store watching everything going on. Three man crew and the Navigator had this roadway type map but instead of roads it was air lanes in the sky, kept checking reference points on it.....it was really cool!
Prior to that I thought fixed wing pilots did nothing after takeoff but sit on their arse and watch the scenery go by. They actually had stuff to do up there during level flight. Well every once in a while anyhow.
I am sure with 9-11 it is probably a big No-No now. It was probably seriously frowned upon back then.
I hung around with a bunch of Huey Pilots when I was in Germany. One trasferred to the Air Force and about a year later, was flying C-5As out of Dover. He did a couple flights a week from Dover to Rhein Main or Ramstein. We'd meet him at Rhein Main sometimes. He said, once they took off, they set the auto pilot and did nothing until it was time to land. He missed flying nap of the earth in a Huey at 100+ knots. Got paid more to fly the C-5 though.
Flying on military fixed wing aircraft is very different from flying on a 121 commercial airline.
Military pilots are just that, military pilots. No civilian airline allows jumpseat privileges for military pilots. Airlines don't even allow jump seat privileges to other airline pilots if they are not in the same company or reciprocating companies. Why would military pilots get that perk?