Ok along the lines of bringing in Buffy style slayers I am working on fitting in the Reapers from the Showtime series "Dead Like Me" along with Gravelings. I'm not up on the mechanics but i think they fit well into the world.

I have to agree. If your Jade court is a major part of your universe then keep them as is and hand wave it. If it was a one off then just pretend it never happened and work in the "cannon" version. personaly I am already compiling a list of alternate sources for ideas that fit well with the style. If others are interested check out the following
 * Neverwhere and Stardust by Neil Gaiman (great fodder for the near and far sections of the Nevernever)
* Thirteen Orphans by  Jane Lyndskold (alternate style of eastern magic based on majong tiles and Chinese zodiac)
* Dead Like Me- A Showtime original series about grim reapers (if you have not seen this watch it. available on net flix instant que)
* The Incarnations of Immortality by Piers Anthony (sci/fi fantasy set in the near future more than likely inspired Dead Like Me)

While it is fair to say that New World Cities may be "thin" with respect to European history there are places that bring more than enough historical baggage and blood. Mexico city had a huge population long before the Spanish arrived Teotihuacan had a population of 200000 people around 500 AD. As for histroical baggage in the south you have the massive deaths of the Civil War, Slave Ships packed with African slaves and Voodoo Add to this the Mound builders of Cahokia, The Trail of Tears, general Native American genocide, Scores that died to feed the industrial revolution (see the Triangle Shirtwaist Factory fire), Big Foot, the Jersey devil, Not to mention the heavy Asian influence in cities like San Francisco and Seattle (you can't tell me that the Jade court has not made inroads along with the Triad, the Tongs, and the Yakuza) If you feel that any major city in the new world is thin then you are not looking hard enough. Don't forget the wild west and the Chicago fire (miss O'Leary's cow my ass) Sorry to get preachy but I teach social studies.

Ok this is strange I am also a Spokane Native and have been working on a similar project. what are the odds. there is some great stuff here. I already adapted D20 modern to the Dresdenverse here in Spokane and ran an adventure were the local chapter of the Hells Angels (they have a club house on east Sprague) was run by the barer of Ursiel.
Some other great fodder here in town.  
Spokane is operating under a Gypsy curse.
 http://seattletimes.nwsource.com/html/localnews/2003765695_marksobit28m.html
check out  the spokesman review cold case files for unsolved murders especialy "Millie" a woman who's dismembered body parts were found at very different times.
 http://www.spokesmanreview.com/coldcase/
Haunted places in Spokane
http://theshadowlands.net/places/washington.htm
1000 steps sight of haunting and "devil" worship
http://spokane.onethousandthingstodo.com/2008/10/31/visit-greenwood-cemeterys-haunted-1000-steps/
this all on top of more than our share of serial killers (Green river, Yeats) I think Spokane will make a great city for the game.