Forget the binary between fiction as a source of inspiration and guides for logistics; the true spark often comes from a practical necessity or an unexpected opportunity.
Neither one nor the other is the sole driver, because we don't always travel for pleasure, but for more down-to-earth reasons.
In these cases, the guide becomes an indispensable companion to optimize the trip, not just a source of inspiration.
For example, when my sister-in-law had to go to Genoa for a medical consultation, she was looking for the best way to get around and affordable accommodation, and that's where practical guides or forums were crucial for her concrete planning.