I would set the story in rural Oklahoma just before statehood (1907). This era still had frontier sensibilities but was brushing up against modernity—perfect for the show’s themes of changing social mores and romantic entanglements.
Character Reimaginings:
Desirée Armfeldt becomes Daisy Armstrong, a traveling actress who’s returned to the small Oklahoma town where she once loved Fredrik.
Fredrik Egerman becomes Frank Emerson, a respected small-town lawyer with a much-younger wife, Anne.
Count Carl-Magnus Malcolm becomes Colonel Malcolm, a proud, blustery cavalry officer or ranch owner.
Charlotte Malcolm becomes Lottie, his dry-witted, long-suffering wife, known for sharp commentary and quiet strength.
Madame Armfeldt becomes Miss Adeline, Daisy’s elderly mother, a former saloon singer turned shrewd landowner.
Henrik could be Henry, Fredrik's son training to be a preacher, adding a religious tension to his emotional turmoil.
Music Adaptation: You'd keep Sondheim’s music but adjust instrumentation to fit a Western folk/country string style—banjo, fiddle, and harmonica in place of harp and lush strings.
“Send in the Clowns” could feel like a haunting country ballad.
Waltz rhythms could be retained but played as more rustic, dance-hall versions.
The Weekend in the Country: The gathering could take place at Miss Adeline’s ranch, instead of a Swedish estate. The ranch is isolated, vast, and full of opportunities for midnight rides, starlit encounters, and secret meetings under the prairie sky.
Themes in an Oklahoma Setting: Romantic misalignment still resonates in a conservative, appearance-conscious small town. Class distinctions translate into landowners vs. hired hands or wealthy Easterners vs. rugged locals. Age and regret have extra poignancy in a place where people marry young and roles are rigidly defined.
Why It Works: The intimacy, humor, and emotional complexity of A Little Night Music don’t rely on Sweden—they rely on people being foolish and tender in love. Oklahoma’s wide-open landscapes and quiet, reflective nights create a perfect environment for those feelings to unfold.