When I play and start the conquest, I usually just raze cities. Like you said, it cripples the economy and its cheaper just to build a settler and start one from scratch. No insurgency and no overpopulation.
I like Americans early on because they build wonders 50% faster. I get all the early Wonders and it carries you through the first 2 stages of the game.
"Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery.” – Winston Churchill
"Your eyes can deceive you, don't trust them." - Obiwan Kenobi