How a bike feels has a lot to do with its construction and geometry as well as the material it is made from... not all steel bikes are plush and not all aluminum ones buzz. I know someone who had to give up her custom ti because it was too stiff and too harsh a ride....

If you see a sale price you like, look up some reviews - see what other people have to say about the road feel.

If you are simply looking to reduce buzz from a harsh riding frame, I'd look at handle bar solutions as well - reducing the buzz on your butt is good, but I think it's probably more bothersome to your hands.