The cardio/muscular condition I'm in only drives how long it takes me to do a long ride. The toughness of my rear end is usually what determines the agony level of the ride!
I did the 6 Pillars century in Cambridge MD this year before doing this 82 mile ride, longest had been a few 65 miles. At the 72 mile rest stop, when we got going again my rear end said "Hey, are you kidding!" The last 29 miles was real slog. Doing this 82 miler after doing 100 made it much easier.
My daughter went to St. Mary's College in So. MD - I mapped out a 100 mile or so ride down there but never did it - from Catonsville probably 120 miles? At the time I didn't like a lot of the roads for the 100 miles, probably would have lengthened it a bit.