Better trading criteria?

When looking at trade offers, particularly buying, I usually have distance ( =time ) in mind. Any ways of meeting trading requirements with 'delivery time' as a variable would be appreciated. I could suggest a few ways of doing this, all make the current UI (two boxes) a bit more complicated.

When buying (I assume) trading assumes the current city as delivery point, so the above would mean that the choice matching city (of a player's many cities) would be crucial, and would have to be worked into the negotiation.

We don't have to reveal everything to the (prospective) trading players; some can be arbitrated by the game. We'd have to be careful about revealing some stats , e.g. other city's caravan speed, though it's possible that diplomats could be used to garner this info for advantage.

I won't expand on the above, until others have had a say... (including whether this is a common enough need to justify dev time).