Just read up on Gate 10. I heard good things, but it's only open to 7 am - 6 pm.
That kinda stinks considering Gen-Con is technically 24 hours gaming which I plan to game as much as humanly possible within 4 days . . . just sayin'.
They go 24 hours for Gen Con. From last year's confirmation email:
"Please bring your email confirmation receipt, along with ID, to the lot located at <your designated lot>. You will need to show the lot attendant on duty your confirmation receipt and ID and then he or she will hand give you a parking pass that coordinates with the number of days you purchased parking for.
Shuttle pick up locations will be marked; shuttles WILL NOT be driving into the lot to pick up or drop off. They have designated locations to pick up and drop off. You do NOT need to call for Indiana Convention Center pick up! Our shuttles will be running 24hrs for the entire Gen Con Event!"