You can easily "expand your way to success" by shoving out buckloads of city-founding settlers i a row, early on in the game.
20+ settlers or more, founding just as many cities + another 20+ city-area settler-developers.
Effective, perhaps - but is it FUN?

Its certanly aint very realistic in historic terms, thats for shure. Also, if the AI should have the same early ultra-fast city-founding strategy for each of the (upto 7) computer-civs; the game would probably grind to a halt, in later endgames.
I have the following four expanding-rules suggestions. They should enable a much more realistic game, and allow the AI to compete more easily (i hope):

A/ Max two "empty" cities (= without any city-improvements) at any given time within that empire, can be allowed. The AI/Human Player HAS to build temple in at least one of above cities, in order to continue founding a new city.

B/ Any city NOT road-connected with some/all of the other cities, gets an proportionally stiff corruption-penalty each turn.
Lack of road-connections to other cities should also give a more noticeable resource-/science-penalty.

C/ A big sized empire of 25 cities or more should be an unstability-factor in itself - increasingly prone to split-up federation-attempts. This should be especially true if the large empire is far ahead in terms of science-/production-/economy- and military might, then the other civs.

(It shouldnt matter if the empire is well maintained: these split-up tendencies should appear anyway, if the empire is self-sufficient and powerful enough (to far ahead the other civs).
The split-ups federations should consist of min 20% - max 40% av the empires cities. A real groundshaker, in other words).

D/ Also (important); the cities in small civilistic-perfectionist 8-12 city empires should in return have less problems with building huge 20+ mega-cities.
Cities in large 20-30 city empires on the other hand, should have increasingly bigger problems with developing indevidual mega-cities.

Did you read the ICS(=Infinite City Sprawl) thread? It analyses this well-known problem from various points of view. Many intelligent (and less intelligent) solutions are offered.

In my opinion the settler itself is part of the problem. Expansion by settlement was the exception in history, not the rule. Some valuable suggestions were made in the One Settler thread.
I'll quote my own idea.

quote: 'I have always found the settler a rather artificial unit. Settlement organized by a government has always been the exception, not the rule. And in 4000BC, when the current CivII starts, almost the entire world was populated, except for some remote islands like Madagascar, Iceland and New Zealand. I still hope CivIII (orCivV) will introduce a rural population, living in villages. As soon as there are sufficient inhabitants in a particular area, small towns will develop, provided they have an agricultural style of living. Further growth should be caused by population growth, but most by migration. I don't expect a more interesting game as a result of the original proposal of OrangeSfwr. Instead it would accelarate the development of your Civ. My proposal would be to let a particular Civilization start with several small towns -only one of them ruled by you- that are not politically united. So you would be forced to aim for supremacy within your own Civilization before outward expansion became a realistic possibility. This would result in fierce competition from the start, being also more in accordance with historical reality.'

Anyway, with Chris Pine from FIRAXIS lurking around in this forum, checking up the latest input on "AI questions", i thought that perhaps any fresh (well, perhaps not so fresh) inputs from me about the annoing ICS-problem might be a good idea.
What do you think? Nothing more to add? Anything wrong with these four ideas? Any summorized conclusions from your own earlier inputs on the subject?