Shocks for 95 Park Ave

On certain sections of freeway where there is a regular rise and fall
of the roadway
our 95 Park Ave Ultra sort of bucks along. It's always done this since
we got it
in '97. Dealer said the shocks were fine. It now has 96k miles and I'm
thinking
about changing them. Is there a better shock that would stablize the
car a bit without
destroying ride comfort, or should I stick with original equipment?

Front, back, both?

TIA

Ed