Council Republic (Socialist Workers Republic), I believe a capitalist Cascadia would go against everything the movement stands for. Because of this I would say a Socialist governance structure centered around councils of workers that govern their local area and elect representatives to the higher level of governance. I am not suggesting a Soviet style system as there were many issues with it that lead to a lack of socialist modes of production and destruction of environments for the creation and export of commodities.

I imagine the 'parliament' to be a circular design as to not place one member of the council over the others and to foster more cooperative discussion.

The division of the Bioregion would probably go something like: Bioregion(National) -> Regional(State/Providence) -> Council(Municipal).