I have two nice ti rides - an IF Crown Jewel Ti and a Serotta Legend Ti, as well as a couple more steel Crown Jewels. My take on steel vs. ti:
If I'm riding on roads with exposed aggregate, the steel bikes transmit a rumble. The ti bikes have more of a buzz, like the rumble frequency was shifted up and to a less offensive spectrum.
If the road is smooth, the ti bikes have more of the "floating on glass" feeling than the steel bikes. There's nothing wrong with the steel bikes on those surfaces, though.
I've gotten to the point where I'm now selling all my steel road bikes and just keeping the ti. Don't need the rumble anymore.