They do training all day every day in these planes. Air shows are probably less exciting than the stuff they practice to do. Also, while they a generically '18's' they are EA-18g's and possibly have enough differences to require maintaining a separate NATOPs check from the other variants. (never flown one so I don't actually know though :). Either way, other than the blue angles who can't be everywhere and don't represent the diversity of platforms out in the fleet, there really aren't dedicated airshow aircraft out there.