I've had my I/S seat reupholstered by Sargent Cycle: it as inexpensive, but more than that it is an extremely comfortable seat. Not every rider will find the aftermarket seats to cure all their "saddlesores" or provide the proper comfort levels for long distance or long saddle time.
I just completed a 98 seat modification using the below website. It was CHEAP and it seems very comfortable just sitting on it (way to cold now to ride). I would say that a Russell or Mayer seat modification would give greater long distance comfort, but you will pay dearly for that long distance comfort.
http://www.ehow.com/how_7501284_improve-motorcycle-seats.html