...I came to the conclusion that big fat tires are the best form of suspension.
+1 on the tire idea.
I toured with a Softride suspension stem for many years since it was part of my Bridgestone MB-1 which became my touring machine. I kept the straight bars but added a pair of Scott aero bars to that. It was an odd combination but fit the bill for the kind of riding I was doing (logging roads in Maine after riding to them from my home in Mass., Quebec 389 from Lab City to Baie Comeau >50% unpaved, etc.)
For the final ride of a series that spanned the continent I swapped out the suspension stem for a rigid one but changed from Schwalbe Marathon Greenguard tires to Compass McClure Pass. The assumption was that supple sidewall tires would serve the place of the suspension stem. I found that to definitely be the case. The sus stem was better adapted to absorbing bigger hits, dropping off curbs, the occasional glancing blow from a babyhead, that kind of thing, but the tires, while not any better in the single hit department were demonstrably superior in cancelling out the road buzz from chipseal, etc.
For randonneuring my advice is forget the suspension and get good tires and run them with lower than max. pressure.