Boystown, Castro, Dupont Circle, South End are all known for being gay neighborhoods (gayborhoods if you prefer). They have concentration of gay residents much higher than other areas which fosters gay friendly attitudes and support gay-owned and gay focused businesses (like gay bars).
I've been looking at information about gay neighborhoods lately because I'd love to have that for AB/DLs. I've read so many AB/DL themed stories where 2 people meet and they both secretly happen to be into diapers. In real life that's a statistical long shot, but what if it weren't. What if there was somewhere you could move where "medical supply shops" actually had enough demand that they could stock products like Fabines and SDKs. What if adult littles trick or treating was just seen as part of the charm of the neighborhood. What if a little accidental diaper peekage was actually pretty common. So many amazing things could come from a neighborhood like that.
I love the idea until you get to the question of "Where?".