Z-man, your observation that Cali States is bigger than SoCal Regional, and is therefore more needing the 2 day treatment is an interesting notion.
The folks in other Regions that will put on the 2 day Regionals felt they had to to manage the number of people attending the event. If any tournament was screaming for the 2 day treatment, it is indeed Cali States.
I know lots of the people who work Cali States, and I know they want to put on the very best tournament experience for the player base possible. I am certain that every one of them dies a little inside to hear complaints about (an allowed) swiss round cut from the tourney.
A 2 day Cali States would be wonderful, perhaps unique in Pokemon State Championships, but wonderful nonetheless.
Maybe, based on success or failure of a future 2 day Cali States, a 2 day SoCal Regional might follow.
It certainly would be an interesting experiment.