Interstices are places neither here or there, nor directly in between, but kind of off to the side and away a little, and not outstanding in ways liable to draw outsiders. Yet when all's added up in terms of daily living, they tend not to fall short either.
Pirsig wrote about them a little in Zen and the Art ... when talking about how to find good motorcycle roads. You'd ride out away from a city, he said, then jog over, and up, then across... until you were no longer on any sort of direct way to anywhere. Yet you're still somewhere, somewhere in between other wheres. That's an interstice.
Living in one, as you might expect, encourages a certain attitude towards the world that's fundamentally different from what's tended to when you are somewhere hustling and bustling along the main stream of humanity. Quality of life becomes more of a focus, or, to borrow another of Pirsig's rhetorical gems, simply Quality.