AHL teams cannot go into Major Junior cities, so keep that mind. Seattle and Portland are out.
Why?
How about Tacoma then? There are other cities in Oregon as well.
Regarding locations in California....
Bakersfield, Stockton and Ontario currently have ECHL teams, with San Francisco (Brisbane/SSF more specifically) getting an ECHL team next season.
I can't see the three NHL teams pushing those ECHL franchises "out of business" by bringing an AHL team to one of those venues.
Oakland (Coliseum Arena) has hosted Sharks preseason games, more than a decade ago, but IIRC, the ice plant would need a lot of work. The Sharks do run the local Oakland Ice skating/ice facility, so this could be a practice location/promotional venue for the team.
Sacramento is trying to build a new (NBA/multi-use) arena, and unless some progress toward that is made before the summer, the Kings may be moving. (And the ice plant needs some significant overhauls. Disney on Ice has to bring their own plant in to do shows there.) Unclear what future of arena will be without anchor tenant like Kings, and whether in this economy there's any possibility of a new multi-use facility being built (especially with public monies).
San Diego has a venue (formerly hosted ECHL team there), some upgrades would be needed. But moreso a better working agreement with arena owner/manager.
Long Beach used to host an ECHL team. Probably some upgrades needed (real close to LA and Anaheim, relatively).
Fresno has 1-2 venues that the former ECHL team used.
NorCal potential venues: Oakland, Sacramento.
SoCal: Long Beach, San Diego
Central California: Fresno