Which bike are you riding? (You have a lot of bikes listed in your signature)
1990s Vintage MTB would probably be the easiest one to set up;. Big fat 26" BMX tires can provide a lot of cushion for rough surfaces, but still roll smoothly on good pavement.
Shown here in 26x2.1" on my old Klein:
A suspension stem , like the SoftRide shown here can be a good retro fit for a road bike; much lighter than a fork, an the bike won't loose as much of it's character. The Kinect linkage stem would be the closest modern version; it has the most travel and best tuning options.
