I also go with the fattest tires I can fit. If 32's are nice, 38's are nicer, and 42's are nicer still. I'm not interested in the debate about whether fat tires are faster or slower. The important thing is that the fatter tires don't beat me up. Last week I rode 138 miles on 28's and I was pretty sore the next day (then again, the fixed gear thing may have contributed to my soreness). But most of my riding is on tires in the 48-53 mm range.
The focus on tire speed as you note in not primary in long mileage, yet IMO how that unit rolls is.. and at what psi. For someone to select any wide tire is a poor choice... many of them are pure dogs. The Schwalbe Marathon for one gets good marks for how it rolls... just for one example.
https://www.bicyclerollingresistance...-almotion-2016
Whole list is there. Some perform better at lowered psi's.. usually the best rated rubber-----> which of course goes right back to ROLLING SPEED.