A regular (non sports) Toyota Corolla will give you the best ride for the money. The Civic and Mazda 3 are great cars but a lot noisier than the Corolla. I would stay away from any Volkswagen unless you are a mechanic or a mechanical engineer.
The new Ford Fiesta and Mazda 2 get high marks for quiet ride as well, but they have buzzy engines unless in top gear.
As stated almost anything will will be a lot quieter and dignified than you current car, even a new Hyundai ACCENT!!!