I saw the Penguin Great Journeys books at lunch today. They are, essentially chapbook-esque. About a hundred pages long. Fit in your pocket. Thematically arranged. The designer of the series has a web page with all the books lined up. Now who wouldn’t want a stack like that one their shelf?
(Which sort of strays into a completely different topic of serial fiction, but I’m suppressing that one internally. Not going to open that can of worms.)