They don't go flat as much.

Here are the OP’s concerns, back before we got into all the usual banter and tangent posting:


“The bikes I have use two different size tires: 700x23 and 700x38. My nominal weight is 190 pounds.
I ride on really rough roads and often encounter glass and other sharp things on the road.
I currently use max tire label air pressure with no problems but if a lower safe pressure would bring more comfort, I'm all for it."

Here is an excellent explanation why his current method is working:

"One factor not yet mentioned is that higher pressure not only eliminates pinch flats, it also reduces punctures, as the trash in the road doesn't get stuck in the tire as often. It's one of the reasons I pump up my tires every day."

If you want comfort, a different bike may actually be in order.
One bike runs 23's? Lets face it - bikes running 23's aren't generally conceded to be "comfort bikes."
The other has on 38's? Without knowing what kind of bike he has these tires on, they could allow for some pressure reduction. But based on the road conditions, I'd say keep 'em pumped up.

Comfort is an amorphous quality. It usually expresses a longing for some sort of "different" ride than what one currently knows. But most often, that is found more in the bikes geometry and rider fit/position, than in squishy, softened tires.