My old Gladiator had suspension seats in it. I ordered a pair from Master Craft that were actually designed to be used in desert and stadium racing trucks. I figured that it would be worth trying because the drivers of those race trucks take very similar blows and similar abuse to what we experience in a boat.
Master Craft can actually build an individual seat to fit a specific person. You tell them your height, weight, shoulder width, etc and what material and colors you want to use to cover the seat. From there, they engineer and build your seat to those specs. They make a world of difference and really do absorb a great deal of the shock.