Hello there, Rabbitmom! Yes, I have tried many supps for fatigue, incl. D-ribose. When people wrote about it, it sometimes read like the militantly touted miracle cures such as guaifenesin, LDN etc., which seem to work perfectly for a few, but not for most. But it's cheap and easy to get and only few side effects, so worth trying. My end result: Initially it seemed a great booster, but I soon realized in the large amounts recommended it was no longer helping, but causing quite a few GI problems. I still use it before special challenges, but it's nothing more than a sort of short sugary boost, like eating chocolate or a Mars bar. Since it actually is a sugar, I'm worried it'll be bad for my general health (avoid simple carbs) and especially my lipids.
The medical evidence is only for CFS and only via an "open-label non-blinded, non-randomized, and non-crossover subjective study", so very placebo biased. It is supposed to work via mitochondria / ATP, something I'd often read and felt might be one of my problems. But it hardly helps me.
Instead and far before that I'd recommend L-carnitine, ALA, magnesium glycinate and malate, CoQ10, ginkgo and selenium, and if you've done that and want to dabble more, then like you say D-ribose as well as NAC, NADH, PQQ and SAMe.
I have a big tub of powder, of which I take about half a teaspoonful in "emergencies", praps another later.