I'm currently playing a very passive civ, pushing most on production, research, and cultural assimilation *evil grin*.
I basically stick with the default govt till i hit republic. The next step I head for is Democracy, switching to it the moment I discover it.
Rep boosts your productivity and happiness by loads and democracy even more. Up till now (1980s), I've only had TWO battles, both involving barbarians, in 2-3000 BC. I'm way ahead in research and all other civs are on my good side.