. . .The PNW absolutely ought to be represented. It's unique. It's cultural achievements are the nonpareil of North America. It had the highest population density in the New World outside of Mesoamerica. However, I do grant Morningcalm's objection that finding a leader is difficult. One could go with someone like Sheiksh I, but it wouldn't be without controversy. They could pull a Kupe and make Yeil (Raven) the leader--but he's even more explicitly mythical than Kupe. (I do not, however, concede that Norway makes a PNW civ irrelevant. Coastal raiding is one direction one could take the Haida specifically, but the Tlingit or Tsimshian would be much more craft/food/culture/faith based. A Warrior replacement with wooden armor would be pretty awesome looking; most fighting was done on land anyway. Alternatively the war canoe could be made an early naval exploration unit that is fast, has little attack, can't go to see, but can pop goody huts.)
Let me add a few Kopeck's worth here . . .
The defining Uniqueness of the PNW cultures was that the area supported the densest population of Hunter-Gatherers in the world. Between the super-abundant seafood (Salmon, shellfish, whales) and shore food (berries, game, roots) they never had to develop agriculture to survive and thrive.
Which means they could have (in Civ Terms) a completely unique Resource model, in which they don't have to build Farm Improvements or Fishing Boats if they don't want to. Give them the ability to get an extra Point of Two of resources from each tile or each Tile with a Bonus/Luxury Resource on it, and they Start Out Unique.
The other Must Have Feature, which
@Zaarin alludes to, is the Cultural Uniqueness, specifically the cultural artifacts:
1. The brightly painted (a form of heraldry, in fact) Head Canoes for whaling, fishing, trading or raiding - talk about your Multi-Purpose Unique Unit! The Haida, Makah and other tribal groups traded long coastal distances with them, and harvested both 'regular' Fish and Whales, in addition to coastal raiding, which was as much about Redistributing Population as it was about destruction. This one Unique could be a combination Fishing Boat to enhance output from Coastal Resources, a coastal raider that, for instance, turns destroyed enemy units into Population Points for the nearest PNW city, and a Unit that extends trade Routes by sea.
2. The 'Totem' Poles (actually, Boundary, Clan/Family, Commemorative, Death, or Shame Poles) which, again, are Multi-Purpose, and the purposes include Culture, Diplomacy, and Loyalty. A Shame Pole was designed to humiliate a leader - foreign or domestic - so potentially, a Monument that reduces the effectiveness of (other Civ's) Governors or Leaders.
3. Plank houses with a distinctive Prow-shaped roofline: PNW Cities could have a very distinctive graphic compared to anyone else in the game, at least for the Ancient/Classical/Medieval Eras.
4. Warriors in Wooden Armor. Again, an absolutely distinctive graphic. This could be a Warrior substitute with extra Bonus versus Ranged and a no-penalty attack from the sea to represent one aspect of the Head Canoe.
Too many possibilities to ignore, IMHO.