I propose that when the economy is implemented, there be some way to deal with all the different currencies that run around, especially with high civ ratio worlds. It bothers me that there is basically no value to foreign currencies at all. You can try trading hundreds of foreign gold/silver coins for a single low quality cut gem, and it just isn't enough. I think there is a simple solution to this aspect of the problem of implementing a good economy system. Money changers. We have them in the real world, and they serve their purpose nicely. Take the example of Urist McLotsacoins. He has a lot of potential value in gold/silver coins, but he has no purchasing power since his money wasn't minted in the civ he is trying to buy stuff in. So, Urist goes to the local money changer. He gives the money changer some of his coins, and he gets an equivalent value back in this civ's coinage, minus a fee, of course. Now he can buy that sock he was admiring.
That alone isn't enough to make this really interesting, since it would just be swapping your coins for other coins with the same properties, just a different name, and fewer of them to boot. The way to make it a cool feature is to have different coinages have different relative worth. The game would plug in some variables to approximate a civ's economic and military might, then get a number out of the equation. It would then compare the numbers of the relevant civ's whose currencies you are trading as a simple ratio. That would be the exchange rate for those coinages.
This produces some interesting effects, ignoring any supply/demand modifications to item value. If you try to buy the same item in different places, the more powerful place would be more (or less, I guess, depending on how you build the equation) expensive in real terms. If I'm buying Item A that costs 100 db in WeakCiv, I would have to trade, say 120 db from WeakCiv to get that 100 db back from the money changer to buy Item A in StrongCiv, also ignoring the money changer's fee.
I think this would be a cool feature. I also think it might end up being difficult to control properly so you don't end up with rates like US dollars to SKorean won. Alongside some feature modifying prices depending on the supply/demand/danger of the location you are in, that would make an interesting dynamic for players interested in doing a lot of trade, and would make certain trade routes more desirable than others, adding another potential political factor to things. Also, establishing a fort or camp along a trade route could make for some very interesting gameplay. (yey tariffs and proper banditry risks, as well as higher invasion potential)
Since I'm new here, I was wondering if it's okay to talk about UI suggestions for the vanilla game, or if I shouldn't bother and just go to modders for the stuff I want. Like seriously, I just want to be able to re-stack my arrows/coins and drop/put/wear multiple items with one menu interaction. The re-stacking can be manual so the game and dev don't have to do as much work when you pick up something. That'd be like a dozen lines. I relish the challenge of a learning cliff, but these things are basic game design...