The current civ sytem, in many ways, doesn't make sense. A lot of the civs aren't really civilisations, they're just different countries. How are England and France different civilisations? They have different cultures and languages, but they are, pretty much, part of the same civilization. Yet, in the game, they are treated as if they are as different as they are to China.
So, my idea is, to change the way civilization is represented in the game. Instead of having twenty-something civs, there would be only be around 6 civilization groups (European, Mediterenean, Indian,etc). Because there would be less civs, they would become much more unique than the civs are now. Instead of just having one or two traits and different colours, they would have many more traits, different art styles, and many unique units. They would also have different names for the same basic buildings and units(instead of having a 'coliseum', for example, the mesoamericans would have a 'ball court'-but it would be exactly the same thing, just with a different name and graphic).
Not to say that you would play as a European. Every civ would be divided into many nations. But the thing is, these nations would be essentially the same as the other nations that belong to the same civ-just with different cities, leaders, attribute, and a unique unit in some cases (such as samurai for the Japanese). But, at the same time, this would allow for many more countries to be included in the game, since their 'importance' or uniqueness wouldn't be an issue-it would just be different names (Canada could never exist on its own civ-but what if it were a country thats part of the 'American' civilization?).
Also, these nations would act differently towards the other nations in their civ-they would feel a little more united-when they would be fighting against another civ's nations, at least). Also, if one nation conquered all the other nations in their civ, they would have the option to rename their nation after the civ as a whole. This wouldn't just be a different name, however, because it would also change the empire so it gain the extra atributes of the conquered countries, and it would increase happiness-and start a new nationality which would eventually assimilate all the other nations in the civ
That's such an awkward sentence. I'll use an example. When the British would conquer the French and Germans, they would then be given the option to rename their country Europe. Europe would then take on the attributes and unique units of France, Germany, and Britain, as well as the common European units/attributes. Because they would be part of a common empire instead of a foreign empire, the French and Germans would be happier. Also, a new European nationality would be born, which would eventually assimilate all the other European nationalities, which would increase happiness/production/loyalty of the empire.
OK, you're thinking I'm an idiot. It's all very well and good to add more common attributes to real-life civilizations, but it removes strategic depth. If France and Britain are essentially the same, then there's no reason to pick one or the other. Yes, in that case, it does remove strategic depth. But it also adds more depth, but in different ways, because it would revolutionize interactions between nations. And you could always just pick one nation per civ if you want them to be utterly unique. And another bonus. Like I said, these changes would allow for more countries in the game-instead of having a 'Native American' empire, you could have an 'Amerindian'(for lack of a better word) civ, which would be subdivided into many smaller nations-the Sioux, Iroquois, Mohawks,etc. Which would be great for the people who dont notice the added differences and just want to go "haha, Im the British." And they would, after all, be more unique than they are now.

That's unbelievably long. Quick Summary: Instead of many civs, there are around six, more or less. These new civs are much more unique, and are divided into many identical nations. These identical nations have common ties with each other, for diplomacy.

I like this idea. In addition, they should add cultural diffusion between the groups. For example, if a Mediteranian civilization took over a Mesoamerican city, the Ball Court should not be replaced by a Colesseum. Instead, it should remain a Ball Court until the dominant Nationality of the nation swiches from Mesoamerican to Mediteranian. Also, that city would continue to produce the Unique Unit of the existing civilization, for example, if you took over a Japanese city, but where Germans, you could make Samurai for a few turns.

Also, when you are making your civilization and choose the name and everything, you should be able to chose from a list of 6 or so Unique Units and Buildings. Maybe you can select two or three units. This makes it so you can have multiple civilizations of the same time that are similar, yet different. The computer would randomly chose the buildings, units, and names from a list.

I like the germ of this, generally I like the idea of pulling things back and generalizing; the ball-court example is, I think, the heart of what makes this a good idea.

I do think, however, that the distinctiveness of the individual nations can be preserved a bit better, both with keeping the traits of their leaders and with providing each one with (at least) one UU or UB.