I think a system like the national ideas in EU3 or policies in HoI3 would be pretty nice to model that. Just pick some ideas (some of which should conflict) and thus create a state. New ideas are added with research ("We have researched social state. Absolutelty no scribes allowed." or by decisions or events (e.g. the "revanchism" when you lose cores and are nationalistic).
Ideas could relate to economics, education, science, various areas of politics, etc.
National Idea "Bureaucracy": Clerks conversion rate +5%
National Idea "Sponsor Railroads": Capitalists build more railroads. Capitalist tax rate -10%.
Or something like that.
Oh, I like that. A lot.