I feel the opposite. I hated the floatyness of the coil loaner vs my air susp. same 21" wheels but the coils have an extra bounce when you go over a bump or frop off of a bridge deck taper. My wife thought the same thing. she didn't drive the loaner though, just passenger ( she was getting carsick in the loaner just driving around town!)
Any coil suspension car that feels like its bouncing has a problem, likely with its dampers. A properly-damped car will have no rebound, as the bounce creates lift on the wheels, reducing traction and creates a very dangerous situation. Considering, what 98%+ of all cars on the road have spring-based suspensions, if you got in one that was bad enough to make you carsick, clearly there was something wrong with it.
The reason the air suspension's ride is more comfortable is that it is slower through the transitions, a sensation when taken to extremes is usually referred to as 'floating.' A car with a coil suspension transitions faster, and when that transition is a bump or pothole, it results in a more sharp sensation than in a car with an air suspension. Taken to extremes, these fast transitions are usually referred to as being 'harsh' or 'punishing.'
Further, damaged dampers are a common failure case for a car with a coil suspension, which involves allowing the spring to over-correct after a transition. In this case the car bounces subtly. Sometimes you'll see a car on the highway that's bouncing noticeably on a flat surface. This is the extreme damper failure case, and is very dangerous. Stay far away from those vehicles.
It's also important to note that the above is from the perspective of someone in the passenger compartment. A passenger compartment resting on an air suspension may react more slowly relative to its coil counterpart, but that doesn't mean the wheels do. It's possible to have a great-handling car with slow transitions communicated to the passenger compartment (indeed this is the holy grail of suspension design), and a terrible-handling car with fast transitions. As such, understand that the above makes no value statement about the pros/cons of air vs. coil.
As far as the value judgements, there's been some great threads:
Deciding on suspension, how does everyone else about air vs. coil?
Is the air ride suspension a feature? | Forums | Tesla Motors
S85 vs P85? - Page 4
And so on. In summary, if you're on the fence you
really need to drive them, back-to-back if possible, and decide for yourself. If you have any questions you feel are outside the scope of this thread, just PM me, I'd be happy to help. While by no means an expert, I do a lot of suspension tuning on my track car and would be happy to help where I can.