Comfort Ride

Hello,
I used to have Buick La Sabre and now I have Impala 03, 3.8L
What can I do to improve the ride to make it feel as the buick or similar (ship in the sea feel)

I take it you have an LS? I think the sedans ride better but they don't seem to have the 3.8l motors, I would also like to know if i could make it ride better.I also have the LS 04 Impala. But i'm think thats there's not much you can do. Tires might help but not help enuff to justify the cost. Buick seem to have a better ride, and I know My Impala will out handle my buddy Buick anyday of the week So it's a give and take kind of thing.