Lots of upgrades help- but the best one was the Motorcycle Larry riser plate. That made all-day riding enjoyable, it was just enough change in riding position to relieve my back and shoulders.
Another great upgrade was the Motorcycle Larry passenger peg lowering kit. The wife says it makes a tremendous difference in her leg comfort with less knee bend.
Have to agree with others about the cruise control- and wouldn't have a touring bike without it. Cruise helps avoid speeding tickets on a bike with such effortless speed, and it has to improve safety because I can keep my eyes on the road ahead without constantly looking down at the speedometer.
All in all, it is hard to rate farkles- each one plays a part. Tank bags, tail trunks, electric outlets, EZ Pass, GPS, better seats, intercom, garage opener, helmet hooks, bigfoot, etc, etc . . . . all of them improve the experience in different ways.