I propose that Fallout 5 should not be set on either coast. Not New York; not San Francisco. Nor should it return to the Chicago setting of Tactics. No; it's time to break entirely new ground.
Fallout 5 should be set in the area between Saint Louis, MO and Memphis, TN. Yes, it's a large swath of country, but no larger than the Fallout 76 map. And it includes both the St. Louis gateway arch and -- more importantly -- Graceland.
C'mon, don't you wanna see the post-apocalypse version of Graceland?!