Where ever you heard the Ram suspension is not up to the task you were told wrong. The payload of the ram I think is highest of the three and handles my camper and horse trailer great. I have air bags but those are primarily used for the horse trailer.
The vibration issue plagues both the Ram and the GMC trucks. This is because the frames are so rigid that they transfer any vibration to the cab. I would say that most of the vibration is coming from the tires being out of round or out of balance.
On second thought, are you looking at a SRW or DRW?