In Downton Abbey, the setting highlights the relationship between the aristocratic family and their servants. It’s used within the storytelling, notably by giving the servants more power downstairs than upstairs (and vice versa for the Crawleys). It leads for awkwardness and threat and humiliation at times. Of course, the effect of the house would not be as stark today, so the time periods of the series are also an important part of the setting.
Mister Roberts depends on its setting, a ship far away the action of World War II, crowded with anxious sailors. The dilemma for Charles (the Hugh Grant character) during his wedding in Four Weddings and a Funeral would not be as fraught if it were set at a county court house in front of a few witnesses. Putting it at a cathedral with everyone important to him and to his fiancee present raises the stakes to an intolerable level.
When you have the chance, go for a boldface setting that emphasizes power, increases jeopardy, and makes escape impossible. And set it up to irreversibly transform a relationship.
Here are a few things to consider:
What is the intrinsic cultural value of the setting? Is it owned by an important person? Is its history relevant (to everyone, like Downton Abbey? to one person, like Scrooge at his own grave?)
Who chose the setting? Did the character magnify his/her power, or choose a place that would benefit someone else? Whose comfort zone is it?
Who’s there? Allies? Foes? Witnesses?
Does time of day or weather matter? A summer evening might be peaceful and lull characters into a sense of security. People might be agitated if they are missing a meal. Blasts of thunder and torrents of rain might put characters on edge and make them more likely to expose their true feelings or just to be rude.
Does the context matter? The same words said in a restaurant or an office or in bed could have different meanings and with consequences severe or slight.
What holds the people there? People look for exits when scenes get too emotional. A writer needs to hold them together. The constraint could be as physical and obvious as a jail cell or as complicated and layered as loyalty.
Is everyone dressed appropriately? For many cultures, this can encourage acceptance (which may be unwarranted, as when a spy wears the uniform of the other side). Or it can lead to rejection. (I once had to go from casual research to the CEO’s office, where anything other than a red tie, a white button-down shirt, and a pinstripe suit was considered gauche. Memorable. I was wearing my relationship to everyone else present and putting myself and my boss at risk.)
Are social relationships intrinsic to the location and unavoidable? A female student at my all boys high school could not be missed. She’d be out of place.
Of course, there’s no requirement that the setting is planned. If you walk into a bar and see an old sweetheart, it may be a complete accident. And it can force interesting conflicts, like having to introduce your current lover to this person — who may have changed in disturbing ways, who may have broken up with you, who may still hold your heart.
It’s a valuable exercise to look through the scenes (especially the key ones) in your work and just focus on the settings. The most important question to ask is, could a different setting shift the relationship, even create a crisis? If this never happens. If, as I see often in manuscripts, scenes seem to take place in cliche places or, worse, what might as well be white rooms, this offers a great chance to revise the work to bring out more of the relationship between the characters. So go for the boldface settings.