maybe well-chosen advertisements would help to while away the minutes spent in verticality

Hmmm, nothing like as pleasant as looking at ads as you go down on an escalator, though (which I also have enjoyed ). Dunno, seems to me that descending on an escalator is best - otherwise you get the bottom of the ad first, which isn't usually the way it's designed to be read.
The lateral movement is also helpful, perhaps because reading is a lateral thing.

I can't see how the experience would translate to verticality.