Having driven Rams with and without the air suspension, I would say that the tire size affects (my) ride comfort more than presence of the air suspension does. Drive both and compare for yourself to be sure. 22" wheels with air suspension rides harsher than 20" wheels without air suspension. Don't get 22" wheels, regardless of suspension, if your back is sensitive to a harsher/firmer ride.
For me, the greatest benefit of the air ride is the ability to easily adjust the ride height for loading/maintenance. There are also auto-leveling benefits for towing/hauling. Personally, I would have opted out of the air suspension if it wasn't included in the Limited trim level.