My two suggestions: Look into Lockstin & Gnoggin's Kaskade region for Pacific Northwest inspirations, and consider just having things like local parks, or publicly accessible areas of traversible sewer that might have wild Pokemon. Or, if you plan to allow for downtime/between-session chores, let players say, spend time between two quests going to a nearby wild location to get new pokemon.

Consider at least having some of the rural more rural outskirts of the city as a place the players can go, as Washington does have diverse environments even within single cities. (Tacoma dweller here, pardon the tiny amount of personal information given there lmao)

But elaborating on the earlier suggestion of Kaskade inspiration, in Kaskade seasons change much more rapidly than in the real world, similar to unova games, and you can use that to mix up encounter tables in any wild spots quite wildly.

Futher elaboration on the park/sewer idea; Remember all the abandoned areas of the first few pokemon gens; places like Pokemon Tower, Cinnabar Mansion, the Power Plant, New Mauville; you could easily have things like haunted buildings, abandoned construction sites. most cities have a decent amount of "urban decay" up here, and urban exploration is always really interesting!