hey sid (or whoever reads this),
i'm civ-fan since 93, when i bought civ1 for my atari st
now i have two ideas how to advance this already great game.
in addition to both, i would add more turns to make the game longer, and both topics give you enough techs and improvements to fill the extra time.
first, storeable ressources.
once you discover a new ressource, you should be able to build in each town a special storage for each type. each store, lets say an oil tank, stores 10 units of oil in this city. with a dozen of citys, that would make a total nationwide storage capacity of 120. put a small display in one corner of the screen to monitor what you have (oil: 27/120).
every oilfiled would fill your store with 1 unit per turn, so it would be a nice task to gather as much ressources as you can to secure a decent flow.
the point is, it is very difficult to trade a whole ressource, because 1. you probably need it yourself and 2. you don't want become an opponent able to build units like hell in 20 turns. i guess its easier to trade a certain amount of a ressource, so you can control how much advantage an opponent can take out of the deal. if you sell 16 units of oil, you would face max 16 tanks in case of war. give your ally some oil, so that he can give you some serious help.
i think this would make the game less monopoly and would raise the importance of diplomacy. in my last game, there were only two oilfields on the whole standard map, both on egypt territory (guess who won).
the second idea is to make the game more individual. its based on the uu feature, which i like, but i think that's not unique enough. i would prefer to create my own special units instead of copying the ones of the real history. if you have no oil, what sense does a panzer make?
creating own special units sounds too complicated, but i think its not. everytime you discover a tech with a new unit, there should be some extra techs, two per unit or so, that are not necessary to advance further in the tech tree. they are only there to make that type of unit better. you could go through the game without any of those upgrade techs, using only standard units if you want. but if you like individuality, make your units special (and lose some turns of science thereby). this could slow down a bit a great power that wants to show its greatness by creating own units.
lets say you discover the archer, there could be one upgrade better arrows or better bows, that give you better attack. it could also be better defence, more movement points, higher visible area, higher bombardment range, less production costs, whatever. so, if you upgrade better bows, you could give your unit a special name. call it superbowman if you want. wouldn't it be cool to let the opponents military advisor say "the best unit of them is, what we know of, the superbowman (archer)"? such an upgrade could also be a nice trade item. these units do not need special appearences, let them look like the old ones, just with different namens.
so thats it, besides i would really love to see a civilization world in fully 3d

why should this not be possible? there are so many awesome worlds created in 3d all over your gamestore, just put a grid on it, like in earth 2150. you need citys, units, field improvements and animations. i don't think its impossible, so come on

. i would love to smoothly zoom in and out, turn around or change the view angle. more ambient sound effects, like owls, when your screen is centered an a woodpiece. woodpeckers, ****oos, cold windnoise in mountains, train noises on railroads, perhaps a post horn in earlier times, city noises, each more loud or more quit, respect to your zoom level. i want to get into my country and my population. perhaps day/night change that moves slowly over the globe, but does not have any effect on the game expect of looking nice

i wanna see forests swaying in a decent breeze.
perhaps one or two additional govenrment types.
so go, make the greatest game of all times even more great, and i'll give you my money.