Our P85 has air suspension. I originally was leaning towards not getting air suspension due to longevity/durability concerns (we plan to keep our car a long time), but in the end, the CPO car we decided to get had so much going for it, we decided not to hold the air suspension against it.
Now that we have it, I'm really glad. In normal day-to-day driving, its really not something you need to fiddle with, but there are always driveways that will cause the nose, tail or belly to drag. People who post here saying "you don't need air suspension unless you drive in the snow" are probably people who aren't too bothered by scraping the underside from time to time. I personally hate to rub the underside of any car I drive, so whenever I see a situation where I'd be worried about scraping, I raise the car.
Whenever we scrape on a new driveway, we just set the suspension on very high and we never scrape there again. I also appreciate the self leveling feature as well for carrying heavier loads (people/cargo).
The air suspension components are from Bilstein. I drove an 85 loaner with coils (21" wheels, same as our car) over 300 miles, I'd be hard pressed to be able to tell the difference in ride and handling.
So, if you're like me and you never want to scrape the bottom, and you're tech-minded enough to remember you have the ability to raise the car, get the air suspension.