Scrutineering - crowds are big, but you can walk around a lot. During some of the downtimes you can run into drivers casually strolling around the place prior to their cars being scrutineered; this is how I managed to snag a photo op with Darren Turner and Bruno Senna on scrutineering Monday this year. There's some stuff going on on the side as well, the ACO driving school had one of its simulator rigs out there.
Autograph session - madness. If it was this bonkers, this jam-packed and crowded this year, next year it'll be far more manic; I was among the first in line and yet I spent 20 minutes trying to make it to the Porsche LMP1 table. So if you want to score autographs from everyone in the 1.5-2 h of the session, my advice is FORGET IT. Pick 4-6 teams and queue up for them.
This post was written on Tapatalk while on a bus trip, so everyone else please feel free to add a lot more details than I could give now in a hurry.