Ride dynamics

I have a 2002 with no modifications. It has 180,000 miles. Original drive battery, heck easier to say I have only changed tires, oil, filters, spark plugs (once), and replaced that coolant pump behind the driver's side headlight. While the car has never driven comfortably we are now 20 years older. The car still gets 45.1 MPG average (over the last 2900 miles) and gives us no issues other than comfort. The driver's seat has always been too firm and poorly shaped. We have tried the various seat cover solutions with no perceivable improvement. We are both over 6' tall.
More recently we have found the car seems to translate every grain of sand into bumps and grooves are jarring. All four corners pass the standard "bounce test" for suspension. We know it will never be a Rolls Royce, but it would be nice to have a more comfortable ride. I have read the tire pressure discussions, and keep the tires at 35/33.
ANY suggestions would be welcomed because at present we drive the SUV for trips over 100 miles; which we now do more often than we used to.

Thanks

 

This car....
180,000 miles, I haven't even replaced brake pads, though I do believe I replaced a rear bearing (spindle) about six years ago. Last time I rotated tires I pulled the rear drums and there was plenty of shoe left. Fronts have substantial pad left and the disc is smooth and true.
I am running General Altimax A/S tires I bought at least three years ago. We have driven coast to coast once in this since then and My wife puts about 900 miles a month on it plus whatever I drive it for. Yesterday we took a country drive, about 100 miles, discussing an upcoming trip of about 800 miles round trip and decided we decided we just couldn't justify the level of discomfort over the savings in fuel. That's saying a lot since the SUV gets 22 compared to the Prius' 45. We are willing to double our fuel expense in order to drive comfortably for what? 12 hours?
There has to be some way to soften the ride. There has to be.
Bushings look good.
Like I said the bounce test is normal, bounce the corner all you want it will settle right into place.
I had the opportunity to observe the Prius in motion from another car. All four tires tracked well, no rhythmic resonance bouncing, no running dribble on any corner. For all purposes it rolled along completely normal. I watched at speeds up to 65 MPH and in town at speeds of 30 MPH as well as several transitions stops and starts.
I do not think anything is WRONG, it just is too stiff. It is a lot like my lawnmower for drive feel. Jarring.

 

I am dropping the tire pressure to 32/30 as an experiment. I cannot do it today but will have the car tomorrow to try it. Then I will likely end up taking the CUV on the trip Friday Morning. Had hoped to sort something this week.

 

Well...
Dropping the pressure is definitely a better enough ride that my wife commented she noticed a difference and what did I do? I drove it some and yes, better ride BUT not good enough. I'll be trying something else if I can find something else.
It affected average mileage, dropping from 45.1 average over 2700 miles down to 45 in about 200 additional miles. I have reset the counter to see what it gets.
I am hesitant to deeply change pressures for tire wear concerns.