sydeshowbob -- Bilstiens or Ranchos for the shocks. Some people like the adjustability available on some of the Ranchos for towing, daily driving, etc.
I don't think I've heard of anyone replacing the springs or leafs as part of a scheduled service. If you have concerns about load capacity, then replacment may be necessary.
Now might also be a good time to service the rear axle with a fluid change.
Cheers from Claremore, OK!

Dave