Status is an important thing to the rich and the famous, the influential and powerful. The best horses, the best hounds, the best looking children and the best drilled soldiers and mercenaries. Itis all vital to the image of the near divinity that the better off often wish to present to the rest of the world (Not counting the eccentric millionaires who wear regular clothes and slum in the regular taverns)
Princess Avenue can be located in any major city, but most likey in A. the capital city, or B. a major port with a temperate to tropical climate. Dukes and duchesses, Kings and Queens, even of other kingdoms will endeavor to purchase, or lease a residence on Princess Avenue as a summer home, as a show that they are not poor, or lacking in worldliness. Two things come with Princess Avenue.
The first is the upper class merchants district. This is the Fifth Avenue or the fantastic realm. The silks and rare clothes are sold here, where a talented tailor or seamstress can make themselves wealthy with a few words of praise from one prince or princess. Chocolatiers, confectioners, jewelers and makers of shoes and handbags are hotly contested commodities. During the summer months, the shops are constantly full, and even do brisk business during the off months as the less than wealthy nobles buy the clothes of last years fashion.
The second is the ‘Finishing School’ a place of worldly learning outside the private tutors of the palace. Nobles meet one another, and form bonds of friendship, or hope to. More than one Finishing School Rivalry has turned to skirmishes to the brink of open war. The golden children are drilled on calligraphy, horsemanship, falconry, heraldry, and the like, some venture into mathematics and linguistics but this is not required.
This is a rarified place or wealth and power, often detached from the rest of the world. There are no beggars and few thieves. The city watch is very vigilant and most of the households maintain their own security in the form of family retainers, or mercenaries.
Kidnap the Prince/Princess - A take on the standard plot, but it is a rival Prince/Princess who has kidnapped a rival to prevent them from showing them up at an up and coming social event. Things are made more difficult as half of the residents could be suspects, not counting the usual evil mages, and the like.
Heir of the Evil Mage - Evil mages could have families as well. Evil mages also tend to be wealthy and powerful also. The daughter of a known evil mage takes up residence on Princess Avenue, and hires the PCs as guards as the rest of the residents blame her for anything amiss or bad. The may, or may no be the guilty party. More interesting if one of the PCs falls for the evil Princess, or Evil Prince as the case may be.
Spring Break - Its Princesses Gone Wild during the Feast of Vines, a time of debauchery following the springtime opening of last year’s wine. A time of wild parties, gala balls, brinking contests and the like. Mardi Gras, plus Spring Break, plus Standard fantasy. The woman with the peacock mask could be a bar wench, or she could be the blooming queen of the kingdom. Drinking buddies become lifelong contacts, assassins arrive to do in a VIP. Everyones invited, let mayhem, and merriment ensue.
I envision Princess Avenue being in some place like the fantasy Equivalent of Fort Lauderdale, Florida, New Orleans, Louisiana or Padre Island Texas. (Dont know the go wild places in Europe, or I’d list em too)
There could very well be a Princess Avenue in the cold mountainous kingdom, but instead of spring break, it is Aspen skiing and snowsports, cuddling in fur and getting drunk on vodka. The shops will tend to cold climate goods and cold climate food. The wealthy and the elite can congregate anywhere.