My head hurts now! Ugh.
...
I know I have not answered the questions directly that you have posed Blazenclaw. I'm still trying to digest your and Toffer's discussions. Just saw them now.
No worries at all, sorry it is so much text!
My 1st point of contention is this: Culture going out past the 3rd ring of ANY city should have a much much lower value than it currently does. Reaching out into the 5th and 6th rings in the 1st 2 or even 3 Eras just does not play nor feel right.
I do agree with this as well, but it is rather difficult to balance in practice.
Right now, the amount of culture needed to level up a city roughly doubles each level. Changing that is difficult, because then it will need to be rebalanced as buildings get rebalanced, and can easily lead to situations where cities may fly through levels too quickly in some sections or take too long to go between others.
I do have some tools when it comes to Realistic Culture however. It is possible to increase the 'difficulty' of terrain and feature types by various factors, including whether a player has tech. Right now, rivers provide a greater barrier until bridge building tech for instance, coast/sea/ocean have greater barrier until you have the tech to trade on them, mountains until you can settle on them, and all features cost more until there is an improvement of some kind on them. Are there other such tech-unlocked combinations you (or anyone else) can think of that would make sense to implement? More of these could cause (potentially significantly) slower culture-on-tile growth.
Question to both @Blazenclaw @Toffer90 what would be so wrong in adding some Culture to the storyteller line of units when used in both Teaching or Patriot mode?
Do we have tags that can actually do that right now? Serious question because I planned to add it but am not sure I did - we have ones that give properties and ones that give happiness +/-, but I'm not sure we have any that do this. I think it would be a great idea if we did.
Don't think we have tags, but should be possible. Teaching AI proper use/evaluation of them of course, always another story.
Basically it'd be a way to turn excess

into

which... I guess could make sense? Whereas using them for culture bombs would be

->

, so both would have their place.