Diplomacy needs a "what will it take to make this deal work" button.

well, that however would always make you trade with 100% efficiency. I think the current system (with the trading partner responding to your offer and telling you what exactly the problem is / the font changing color) is a pretty good solution. But you are right in one point: I often find myself wanting to click "request offer" although that function doesn't exist

Add it then! Why waste peoples time while they go through getting the most bang for the buck. It doesn't add anything to the game, it should not be there. I always trade at 100% efficency anyways, I just waste a lot of time clicking and clicking and clicking to see what is the best trade for me. If I had some clue what the AI values the tech for then I would be a happy camper! Campers are happy!!! We are just joke!

Now on the same note, the AI does not properly value techs imho. Sometimes the gouge your eyes out for a slight weapon improvement and let go a tech leading to an unbuilt wonder for cheap it is generally worth it to then "bounce a check" building that wonder before anyone else. They trade far too often with each other, as has been mentioned.

I would rather the AI simply make counter-offers to your own offers. For example, if you want to take a tech and offer a tech on a one-to-one trade (which would be your proposal), the AI ought to say something like, "We don't like that, BUT we can do that trade if you give us

I would rather the AI simply make counter-offers to your own offers. For example, if you want to take a tech and offer a tech on a one-to-one trade (which would be your proposal), the AI ought to say something like, "We don't like that, BUT we can do that trade if you give us on top of your original proposal." Or quite simply have the AI highlight what they want in exchange for what you want, thereby showing you how much value they place on the given item you want to take from them.

I agree with this.

However, if we had the button like in Civ4, you pretty much remove all haggling. Personally, I like a bit of challenge when it comes to trading, and the lion's share of tedium is removed by the whole "green text vs. red text" feature.

I'd like a "fill in the money" button. Moving the slider to find that it turns from green to red at 618 bc is just silly.

Would very much like to see this or some means of determining the value of the various trade items.

I personally like it the way it is. As far as the value of things, it should be kind of obvious that techs higher up the tree than other techs are worth much more, etc etc. Try trading Laser III for Plasma Weapons. It'll be red. I think mostly it's common sense the way it's set up now. Plus, a race at war is more likely to trade things you want for war-related techs/items/money. A race at peace cares less about weapons, etc. Lots to pay attention to when trading.

However, if we had the button like in Civ4, you pretty much remove all haggling. Personally, I like a bit of challenge when it comes to trading, and the lion's share of tedium is removed by the whole "green text vs. red text" feature.

The button in Civ does not always give you the best deal. You can frequently get a deal that is noticably better in civ if you hit the button then work things around a little. You can routinely save 5%-10%.

The Civ button is supposed to set a "fair" trade. But you can still push the trade from "fair" to "acceptable". You get a diplomatic penalty, though, since the AI knows you're trying to squeeze it.

The button should be implemented. I agree with Soren's take: if you give the player a way to optimize their game, they'll do it. You may as well automate it. That's why Civ IV implemented overflow, because players used to manage their sliders to not waste shields or beakers. With overflow, that's unnecessary.

GalCiv II should make it easier for players to optimize, since all competitive players will be doing it anyways.

I'm wondering: If you give the AI a better deal (by asking less), does that make him like you more?
In that case I wouldn't mind to lose a few BC by not trading optimally. Small gifts go a long way.

I hate the tedium of this system as it is currently set up. There's no brain usage and lots of clicking. If I wanted that I'd play an RTS.