There is actually a level above PC called Platinum. You can't earn it since it is given based upon the amount of revenue you can influence. You might get it if you were a CEO and can make your company switch to Hertz, for example.

In the past, a Hertz agent would actually meet you at the gate and give you the keys right there. Now, they meet you around baggage claim and hand over the car. They take the shuttle back to the lot. I'm sure there are other benefits and better service.

I would say that while the parking info is posted on the site, it's a bit obscure and not something most agents would know. I doubt many people ask about the program or would be interested in knowing about it.