You may not find the Si much better in that regard. The suspension on the newer Si models is a bit improved over the RSX, but it's still going to be pretty stiff...
EDIT: If your RSX is the base model, the Si's suspension may actually be stiffer...
Well her RSX has like 112k miles on the original shocks... its ride has deteriorated nocticeably over the last year or so. but good input nonetheless!