Spring rate will be higher than stock nismo, damping isn't necessarily going to be better, and softer damping doesn't necessarily equate to more comfortable ride either.
If comfort is really a priority here, crazy thought is you can swap your springs and shocks with the sport pkg units....
Flame suit on for this one - or be even crazier, go with Tanabe NF210 springs and Koni yellow shocks...assuming the yellows can withstand the low spring rate.
Spring Rates
Best solution, however, buy a used civic/corolla/whatever for rougher trips.