I personally find that touring posture, bike setup, and saddle choice are all best for me when they mimic my road bike as closely as possible. That includes the bars being quite low (3-4" below the saddle). As a result I don't need a different saddle. I find that setup very comfortable. The key is to maintain good core strength and ride with bent elbows and a relaxed upper body. So no hunched shoulders and fingers draped loosely over the bars.
If you adopt a more upright riding posture for touring it might require a different saddle choice.