Dungeon Boomtown

The suggestion of boomtowns (linked not because you don't know what a boomtown is, but because of the list of historical boomtowns) near dungeons is something mentioned in D&D, but seldom is the concept developed in any interesting way. Chris "Hill Cantons" Kutalik has suggested before that the description of Maust on the border of the Dirdir-infested but also sequin-filled Carabas in Vance's The Dirdir is great for evoking this very thing, and he's right:

By noon Maust appeared in the distance: a jumble of tall narrow buildings with high gables and crooked roof-lines, built of dark timber and age-blackened tile...Running boys came out to meet the motor-wagon. They shouted slogans and held up signs and banners: "Sequin-takers attention! Kobo Hux will sell one of his excellent sequin-detectors." "Formulate your plans at the Inn of Purple Lights." "Weapons, puffpads, maps, digging implements from Sag the Mercantilist are eminently useful." "Do not grope at random; the Seer Garzu divines the location of large purple nodes." "Flee the Dirdir with all possible agility; use supple boots provided by Awalko." "Your last thoughts will be pleasant if, before death, you first consume the euphoric tablets formulated by Laus the Thaumaturge." "Enjoy a jolly respite, before entering the Zone, at the Platform of Merriment."
...They entered a narrow street running between tall, age darkened structures, the beer-colored sunlight barely penetrating to the street. Certain of the houses sold gear and implements conceivably useful to the sequin-taker: grading kits, camouflage, spoor eliminators, tongs, forks, bars, monoculars, maps, guides, talismans and prayer powders...
After a meal of stewed hackrod and mealcake, the three repaired to the library, at the back of the second floor. The side wall displayed a great map of the Zone; shelves held pamphlets, portfolios, compilations. The consultant, a small sad-eyed man, sat to the side and responded to questions in a confidential whisper. The three passed the afternoon studying the physiography of the Zone, the tracks of successful and unsuccessful ventures, the statistical distribution of Dirdir kills.

No quite as on the nose, but with plenty to inspire the town adventures that would take place between dungeon delves is Deadwood (2004). Here's a choice quote adventurers would do well to keep in mind: “Announcing your plans is a good way to hear God laugh.”

The movie Tombstone (1993) that civilizing forces are drawn to areas of great wealth as well as treasure seekers. They are a strange mixture of raw and upscale. From the opening narration: "Tombstone becomes queen of the boom towns where the latest Paris fashions are sold from the backs of wagons." And from Sheriff Behan:

"Have you seen how everyone dresses? Awful tony for a mining camp. No, sir, the die is cast. We are growing. Be as big as San Francisco in a few years and just as sophisticated."

Of course, a gunfight in the streets is ironic punctuation to his comment.