I currently ride both an Ti and AL road bike.

The AL has 25c tires and I pump it up to 115 psi. It has a very nice, quiet, smooth ride.

The Ti bike has a 23c tire and I pump that up to 115 psi as well. It too has a very nice ride, just like my AL bike, but it weighs well over 7 lbs. LESS, plus it has a very efficient drivetrain, so it's easier to ride fast and climb hills in.

If you want comfort, yes, put 25c tires and pump it up to no more than 115 psi, 100 if you want a real cushy ride. But if you want lightweight AND cushy ride, a good quality Ti frame/CF designed for plush riding is even better.

The plus side of the Ti frame is it has no paint so nothing to chip, it does NOT rust, and it just looks cool with none of the overly organic look of todays CF frames. I'm sorry Pinnarello fans but I can't stand the way a Dogma looks!