The wider tires are softer because they run at a lower pressure. 700x25c tires are basically rock hard when fully inflated. Although, having previously had 700x38 tires, I am more than willing to give up the comfort for the vast increase in efficiency and speed from the 700x25 tires I am running now.
You could try Ergon grips, and gloves with good padding. You could also try a suspension seatpost or a seat with springs.