We just started a Las Vegas game, too. In City Creation we decided that there's something about the Las Vegas valley that's a magnet for supernatural and mundane predators of all kinds; the barrier between our world and the Nevernever is thin, but the reason why is tied to some underlying spiritual issue that predates the city by centuries. We tied the glamour and glitz of Vegas to this in one of the themes about Vegas being a lure with predators behind the glamour (I can't remember the exact wording of the Theme aspect). A lot of that glamour comes from the city/valley itself and the predators take advantage of it.
The White Court is dominant. There's a minor house that's hyper-specialized and is pretty limited to gambling centers throughout history and the world. They have very specialized feeding requirements and are more like spiders than hunters. Their emotional control is relatively subtle and acts to disinhibit and cause other feelings to be more extreme and quickly changing. In their casinos, the certainty that the next toss/draw/pull will be the big winner is enhanced, the allure of the lights and counds is more intoxiating, the excitement more invigorating... and the despair of realizing you've spent your entire paycheck more utter and the obsessive certainty that the only way out of your hole is to borrow more and get back in there is more compulsive. This family of the White Court will spend years, even decades refining and "aging" their prey like a fine wine. The downside is that they really don't draw sustenance from a quick prey like the other houses can (one major NPC is an outcast prince of this family who is starving without long-term access to the casinos and so he's willing to bargain with anyone or anything to topple his family and get back in there).
The Red Court are starting an aggressive incursion (which the players decided to make the central threat/focus of the campaign). The Black Court is there in small numbers because it was specifically requested by two of my players. I'm still working out exactly how I want to work them in, but I have several ideas. Vampires of all three courts are a big deal to three of the four playersz: One player is playing an Emissary of Power type that's loosely based on the Slayers from the Buffyverse, another is the new, ill-prepared Warden focused heavily on the red court war, and a third is a knight of the cross who isn't specifically focused on vampires but made it clear that he's more than happy to face them whenever the chance arises. (There's a fourth PC, but she isn't directly tied to vampires in concept.)
In our Vegas neither the Summer or Winter Courts of fae are strong (there's not enough life for Summer and it's too hot for Winter), but there's a renagade minor court of fae that acts as a haven for fae outcasts--the Court of Fools. The COurt is led by the Fool King and they also run the local Neutral Territory. As befits the fae, the Fool King and his Court of Fools are very ambiguous and mysterious.
There are a fairly large number of minor talents, mid-level warlocks, etc. I'm stealing the idea above that there's a strong supernatural black market (I hadn't thought of it but it fits well for our campaign). The old warden was killed early in the war with the Red Court and one of the players is the new warden (he was the old warden's apprentice) though he isn't really ready for it. The local magical community is led by a fairly powerful ceremonial magician-type (focused practitioner with full Thaumaturgy but no Evocation) and her cabal who hated the old warden and is very hostile to the new warden PC. The local Paranet is being targeted by the red court in the opening salvos of their invasion of the city, but their leader (well, as close to a leader as they have) is all but forbidding them to go to the warden for help. Her cabal is trying to act as the local "wardens", though with limited success. If the local practitioners and the White Council would work together, they'd be in a much better position to oppose the red court or even just keep themselves safe... but I'm not going to make it easy for the warden (he also intentionally took pretty weak social skills and an aspect about being inexperienced because he likes the idea of having to stumble through this kind of scenario--he's competent in a fight but the other parts of being a warden, particularly in a hostile city, are a struggle).
Also Lady Luck (sort of an Emissary of Power) is in the city and is a big player, though mostly through the effect she has on her surroundings rather than conscious plotting. She's a wild card and has a tendency to shake up the status quo. Plus she enjoys tormenting the young warden PC, though she's actually fond of him. As the player and I have talked about it, it's going to feel a bit like Mab with Dresden--though the "offers of power" and the chaos she enjoys causing him are more in the line of "tests". She's like a hurricane at times (though at other times absolutely nothing strange happens for long stretches).
Finally, there's a small but significant undercurrent of things angelic and fallen going on in the city (in part tied to there being a knight of the cross living there). I'm using the Denarians (the player of the Knight specifically requested it), as well as some other stuff (such as an escaped Grigori/Watcher, a powerful and scary Anakim/"Giant", and a powerful "sorcerer" who's power comes from binding angels and forcing them to do his will and make him amulets and talismans of power).
-John B.
