Tri-cities
Seattle (Key Arena and ShoWare)
Everett
Portland (Memorial Coliseum and Rose Garden--I refuse to call it the Moda Center).
Of those:
Rose Garden is the best hands-down, and could easily handle an NHL team. Great seating and sight lines.
Everett is 2nd best IMHO. Smaller arena, but definitly loud--which always makes for a good hockey experience. Great sight-lines as well.
Showare is only a little behind Everett. Small, loud, and has fantastic ice; the only way it loses point against Everett is that seat access is from ice level at the bottom of the section, not top; can be congested. Still, great sight-lines.
Memorial Coliseum is 3rd. Smaller ice and defintily shows it's age (especially with the JumboTron that has the best technology that 1996 has to offer), but still retains it's charm. Good sight-lines and atmosphere.
Tri-cities is smaller and a bit more cramped than Showare--basically an arena built into an office complex that somehow works, if nopt perfectly. Decent atmosphere.
Last and certainly least is Key Arena. The architect of this piece of excreta needs to be thrown screaming through the blades of a helicopter. Poor sight-lines, bad ice, and it's definitely telling if the T-birds *and* the ex-Sonics couldn't leave there soon enough. Place needs to be carpet-bombed IMHO.