Ken: Thanks for the link. Interesting that none of the more iconic (WHitney, Half Dome, Basic GCNP to the River) trips made it. Rightfully so, as they are all easier.
And while Rim to Rim comes in at #7, Rim to Rim to Rim would be off the scale of these 10 "Hardest Hikes" and numerous folks on this picked that off a year ago (not me, mine was a 28-mile, not 42-mile day).
Still, I'll print it out as a "Death March Bucket List" to aspire to.