I've already got our government system down for our nation. I call it an "Electoral Republic." Here's how it works.
Once every three months, the citizens of our nation elect members to serve on our republic. (Haven't decided how many will be elected.) Then we hold an election for the past representatives of the republic, five of them will be appointed to the "High Republic." Those five will manage their own branch of our society. The five branches are Labor, Science, Commerce, Culture, and Military.
Here is what the branches are about.
Labor = Mining, Farming, and construction projects for public buildings.
Science = Redstone distribution , brewing, and operations in the Nether.
Commerce = Money, taxation, and trade between other nations of the server.
Culture = Public projects involving art and religion. (Real religion or a fake one, it doesn't matter.)
Military = Armed forces and production of weapons and tools.
The members of the Republic below them will debate and govern the nation, but will have to have everything approved by the High Republic.
I am still working on this system. If you want to adjust, add, or know about anything. Just let me know.