Whenever I capture a city in Civ 4 I am offered the option to raze it or install a new governor. I almost always choose to install a new governor - after all, why not start with a partly-built city rather than build a new with a settler? The only times I raze the city are:
- The city is so far from the rest of my empire that I have no hope of keeping it
- The city is so close to my existing borders that I would automatically take over its space if it were destroyed
Are there any other reasons I might want to destroy a city rather than take it over?