You can find a fan map of Anchrome on Google (type "Anchorome Map"). The area that pertains to the Pacific Northwest is the wetlands area between two mountain ranges.
My only problem is that I'm not good with names. Other than that, this is looking pretty good. I'm concentrating specifically on a Chinook tribe facsimile (the Chinook were the tribe that Lewis & Clark encountered on the Columbia River).
I would have preferred to post this on the Spelljammer forums, but that place is dead as a doornail.
First, a couple terms:
Blood Feud: A term referring to enmity and vendetta between two or more clans. As wikipedia says: "Feuds begin because one party (correctly or incorrectly) perceives itself to have been attacked, insulted or wronged by another." Blood feuds usually arise because one member of one clan is killed by a member of another, be it accidentally or intentionally. In a blood feud, this results in an endless cycle of retaliatory violence. Many of the harsh laws in Leviticus, for instance, were aimed at stemming blood feuds, which was a huge problem among the ancient Israelites.
Cascadia: An ecological and subcultural region (cultural in reference to the Amerindians) stretching from the SE coastal tip of Alaska, down across the coast of British Columbia, all of Vancouver Island and Queen Charlotte Islands, across the western 1/4th of Washington, Oregon, and northern California (or only down to mid Oregon in some versions). The term is used primarily by BC Canadians and is synonamous with "NW coast region". I prefer the term "Cascadia" because "NW Coast" is a misnomer-- the region stretches inland to the foot hills of the western slopes of the Cascade mountain range (which is sure as hell not the coast)
First Nations: Canadian term for "Amerindian". Same meaning.
Unlike with most Amerindian groups, the Northwest peoples do have thieves and are much more materialistic. Some of the Chinook merchants (according to Lewis & Clark) were also thieves, but adhered to a strict honor system when stealing (could only steal right under the person's nose, had to stick around for some time after the theft, couldn't conceal the stolen item, and if caught, had to give up a cherished possession in exchange for the object they stole. Also, they couldnt' steal something that wasn't under the victim's control-- such as a runaway canoe or something from sleeping victims).
Other available classes include fighter, spirit shaman, druid (druids and spirit shamans use western red cedar and devil's club sprigs for a divine focus instead of mistletoe and holly), OA shaman, ranger, scout, marshal, factotum (Dungeonscape class), and bard. I will look into it more, but I do not believe the barbarian class would be available.
I do not know if the NW Anchrome groups will have their own specialized arcane casters, or not, but sorcerors and warlocks will exist as VERY RARE encounters, mostly as villains living in seclusion (usually in the mountains).
The NW groups also weren't nearly as "savage" as many of the Plains and mountain groups. In fact, the white settlers and traders very rarely got into violent conflict with the natives; while relationships between the two races were always tense, disputes were almost always resolved diplomatically. That is not to say that the NW peoples were somehow less violent than other groups-- they were plenty violent towards neighboring tribes, though wars were almost always the result of blood feuds or the seeking of slaves (huge slave trade among the NW peoples). (there are only about one or two actual indian wars recorded between the NW coast peoples and the white settlers. This is in stark contrast to the Rocky Mountain and Plains groups. This was partly because the NW coast peoples had always associated the white man with trade, and also because, even when the white settlers did displace them and take their best lands, they provided jobs/employment.) The NW lands were lush and bountiful, so the native peoples had little reason to go to war over resources for survival. They also had no reason to practice agriculture, though a sort of proto-agriculture was practiced (e.g. wild food plants were divided, burned, and transplanted for maximum harvest, but actual plantations did not exist here as they did in the Northeast and many other areas). Also unlike most cultural groups, the NW coastal peoples had a concept of private property ownership. The culture here is also vastly different from that of the rest of the First Nations of the time. With the introduction of the horse, most groups adopted a plains culture.
The NW coastal peoples were an exception and retained their traditional culture which was based around canoeing, fishing, and traversing the river systems. You see, the forests of Cascadia are very thick and lush; so much so that horses are useless there. They wouldn't have been of much use in the wetland prarie, either (ground isn't stable enough) (the wetland prarie was a man-made ecological region covering 1/3rd of the Wilamette Valley due to the First Nations practicing annual burns for hundreds, if not thousands of years, and many of our state animals are wetland prarie creatures. Today the wetland prarie has been almost entirely replaced by thick woodland and manmade settlements.) Due to the wetness of the region, the NW coastal peoples also had a different style of architecture than what we are used to in Amerindians. They used "long houses", which were basically very long, communal western-style plank houses. Teepees were not used.
Corn and beans were never cultivated here because it would be useless to do so. The climate is marine-- that is, warm winters and cool summers. Not exactly the best place to grow beans. Likewise, the corn wouldn't have liked the cool, wet climate.
The NW Coastal peoples' form of government was also a bit different from most groups. It was a bit less collectivist and tribal, and more clan-based (such as what you would have seen in Scotland and ancient rural Levant). Many but not all tribes had a chieftain, and the tribes usually consisted of alliances and communities of extended families/clans, each one having varying levels of political power. There were also rival clans-- the Chinook proper and the Clatsop are the best known real-life examples. Though both were Chinook tribes and closely related, they were bitter enemies-- opposing collectives of clans. The reason for their enmity, from what I can gather, was primarily blood feud, and any time one tribe intentionally or accidentally killed a member of the other, this usually resulted in a war.
The First Nations/Amerindian peoples all the way up and down the Pacific mainland coast had a standardized form of money known as Dentalium or tooth shell. The one primarily used is Dentalium pretiosum, known by various names (loqua, indian money shell, indian money tusk, etc.). In game terms, this includes the Azuposi (I will have to find out what Amerindian group they are a facsimile of).
I'm also working on a specific deity list for the region and a bestiary using existing creatures.
The following is a guide in general for creating Anchorome encounter charts and bestiaries using 3x rules:
The types of monsters encountered in an Amerindian setting will vary somewhat depending on the real-life ecology and legends, but in general will consist primarily of the following monster types: Animal (normal, giant, dire), Incorporeal Undead, Humanoid, Monstrous Humanoid, Magical Beast, Elemental, Fey. Certain types of outsider will also be present in some regions.
The exact ecology should mirror the natural dangers of the real-life region.
For instance, vine-type plant monsters would not be present in a Pacific Northwest analogue because there are no large or aggressive vine species native to this region (other than the wild cucumber, that is. This thing is huge, climbs, and spreads like crazy-- getting quite huge, but does not have the reputation of "smothering" or "blanketing" an area-- in many cases breaks will exist between the stalks in which other plants can grow, particularly on a slope.) OTOH, plant monsters such as treants and needlefolk would be present.
In general, the more dangerous the wildlife of the real-life region, the more sub-intelligent and non-intelligent monstrous humanoids, monstrous vermin, magical beasts, and lycanthropes you can drop into the habitat.
On the other hand, safer regions such as the Pacific Northwest (where the only hazards *for adult humans* were bears and the occasional shark-- actually, I think most animal inflicted injuries came in the form of mid-air collisions and strikes from fish.), and in which the primary danger to humans was overwhelmingly other humans, should contain a wide diversity of intelligent monstrous humanoids and humanoids.
Most nature and elemental fey of the trickster and malicious genres can be dropped into an Amerindian setting. Urban, household, mining, and otherworldly fey generally are not appropriate for an Amerindian setting. The fey that can be incorporated will need to fit the description of "embodiment of elemental, plant, or animal spirits".
Corporeal undead save skeletons are generally not appropriate for an Amerindian setting. An exception could possibly be made for vampires as specimens of failed ressurection/raise dead spells, that instead returned the subject to a state of 'false life'.
Bear in mind that the incorporeal spirits and skeletons are not always malicious in Amerindian folktales. There are several stories of characters encountering villages or cities of the dead, which ended up being like something more out of a Twilight Zone or Tales of the Darkside episode than something out of a horror movie (I'm not joking about the twilight zone thing, folks!)
Also, an imortant tip, as a Northwesterner myself, about forest ecology for the NW region: giant forms of monsters don't work well here. They're fine for the wetland prarie and big river systems, and ocean, but the forest is too thick for large creatures. Hell, even the NW Coastal people were rather short/petite compared to some of the other Amerindian groups.
I don't know about further down the coast, but the Tlingit (Southeast Alaska) and the Haida (Queen Charlottes - Prince of Wales, Alaska) certainly went to war with each other and were also known to make battle with the white settlers and explorers. See Katlian's massacre of Sitka or the reason why Escape Pt. is so named. They could probably be lumped in with your analysis. In fact, a campaign set during a "Haida" (or however you name the group) or "Tlingit" incursion could be very intense. Magical items could include Warmasks, Shields, and Breastplates. Totems could become golems of their constituent figures (Devilfish, attack!). Just some ideas.
Treants could look really cool. Obliviax would certainly work ("Memory Moss"? Whole areas around here are covered in moss!), Myconids and other fungi-based creatures, Devils Club is certainly evocatively named and always right where your parties would need to grab it. You got wolves in the forests and mountains and all that goes with that (Werewolves or wolfweres), bears (ibid), and deer (Actaeons). Kushtakas, which were kind of like beaver-otter dopplegangers. With the mountains so close, any rock based life form might work. Galeb Duhrs or Goliaths. Raven based monsters. Almost anything based off of a real animal (Raven, wolverine, wolf, bear, squid, fish, whales of any sort, skunk, etc.) could work in this setting.
And giant monsters could most certainly live inland: in the mountains. At least in the islands, the natives did not do a whole lot of venturing inland, probably due to the thickness of the forests and the extreme topography. This resulted in sacred sites atop remote mountains. At those elevations, the areas open up and provide for areas that could be inhabited by giant monsters. However, these would be of the "magical ecosystem" variety, like an aurumvorax, rather than one that would consume mass quantities (that just aren't present in those areas).