I'm a warmonger/builder. Generally expand to my 3-4 core cities. Then I turtle and build build build. When the time is right for me, I usually start my run taking everyone down in turn. I find it snowballs after the first guy, I'll have my standing army big enough, and my economy will be strong enough that my main cities can go back to just building whatever wonders or buildings I want as my army takes over the world (with an occasionally purchased unit coming along).