I've found that it is small details that help make fictional worlds come to life in my imagination. (For example knowing there have been wars the current regime is recovering from yet the wars themselves are not the actual story).
Characters have to have their own sense of place but the great thing is this can be misplaced, which can lead to tragedies or great comedies. The struggle to improve place/position in society can add depth to a story. Pride and Prejudice isn't directly about Mrs Bennett's wish to marry her daughters off to well connected, rich men but it is the love story of Elizabeth and Mr Darcy. Yet without Mrs Bennett and her ambitions so much of the comedy of the novel would be lost.
I've used my knowledge of places (and what I've researched) to help flesh out my Fairy Kingdom, making it easier for me to visualise and therefore write about. Hopefully it will, in time, make it easier to readers to visualise it too.