I rented from National at ORD for the first time over the holiday weekend. Compared to Alamo, they were an unorganized mess!
The shuttle bus driver dropped about 9 of us off in from of a parking lot of cars and said to grab anyone you like, regardless of what size car you reserved! I had reserved a full sized vehicle so this wasn't a free upgrade for me but I guess most folks had reserved smaller cars since they ran off the bus like it was some kind of "cash-grab" contest! Before I could get off the bus, half of them were already zooming towards the check out booth.
I wanted a nice big Buick or Oldsmobile but ended up with a stupid Chevy Blazer.