Excellent comprehensive job, Seek. Assume I'm in favor as written in the OP except:
1. I would leave the value of luxuries as is. They're worth the most early on, when I have the least access to gold, and worth less as I have more. That seems right - and I don't want to lose most of the early-game investment options because of a reduction.
2. Having unit rush-buy costs being double that of buildings strikes me as too unbalanced, almost by definition. For example, I think it would really hurt in the case of an early AI rush.
3. It seems as if you nerfed gold too much in total, but Thal has already taken a basic crack at gold reduction in the beta, so we can adjust from there.
Similarly, Thal has made an adjustment to RA costs, so let's see how that goes before proposing something different.
4. On a predictive note, if games approach the 350-turn mark, with the human losing some of his edge to the AI, nukes are going to become a major, unwelcome factor that will probably have to be addressed.
1. I disagree, but won't press the point. I've updated the OP with another idea, which is to slow cultural/financial border expansion - half the reason selling luxuries is so powerful is because of the ease of acquiring more luxuries, even in the fourth and fifth rings.
2. Perhaps scaling by era/unit would be better, so we leave the early game alone. We could also exclude Vanguard units so a defensive player wouldn't be too harsh - but that might defeat the purpose.
3. Indeed, I can't wait to try the new beta!
4. At least in VEM we have defense against nukes! But I am hoping for an extension of the game's turns without necessarily extending the actual tech count, etc.
I like the Archaeology idea!
I agree about gold and have been taking steps to give it better status.
1. Happiness (and AI-luxury trades) depend a lot on playstyle. There's an abundance of happiness in tall-empire games, but conquest games struggle for it. I've done a few things to shift this around: Honor give more happiness, while Tradition gives more food to consume happiness. I also eliminated the vanilla Tradition policy which gave happiness directly from population. I've been planning to redesign the later policy trees, so I will look for ways to expend more mid/late tall empire happiness there.
2. A few versions ago there was feedback policy rates were too slow, and people asked for culture victories to be shifted from late-Modern to late-Industrial. If policies were too slow then, and too fast now... I want to avoid bouncing back and forth a lot. I think I'll leave policy costs alone for a while so we can get a long-term view at it.
3. I did not like Civ 4's approach to events. They were random incidents of good/bad luck scattered through the game, and Civ already has luck built into map creation. My goal with the new system is to provide immersive and challenging choices about how to advance society. Free/cheap/expensive tiers are usually not challenging decisions because we pick the best option we can afford.
4. In VEM rush-buying depends on how developed a city is: higher-tier buildings get a discount. If this discount did not exist we'd automatically buy in undeveloped cities, and build in developed cities.
============
I'll respond to the rest later; gotta head off for now.
1. I'm confused - are these undocumented v131.1 beta changes or are these future plans? As I mentioned in response to Txurce above, if lowering AI valuation of luxuries isn't something you think would benefit us, slowing tile acquisition via culture and gold would help a great deal. (It would also increase the value of Stonehenge and the Kremlin.)
What would be ideal, of course, is if the AI valued resources appropriately, valuing them differently in different eras and/or would only give full price when a) at Friendly status and b) needed the resource. (I'm 99% sure this isn't possible with our current modding tools, but I'll pop it into the OP anyway.)
2. Understandable! But that suggestion was "to account for tech cost changes" as I said in the OP - if the tech cost changes aren't implemented there is no need for the culture cost change. But this may be beside the point because Artists and Scientists had their yields halved in v131.1 beta.
3. Ok, I see your point, but right now Opportunities feel like stealing because they're so powerful (and I understand that they will be rebalanced in future updates, so no worries!)
4. I don't see that as a bad thing at all. It
should be easy to set up basic infrastructure in new cities late in the game, and more difficult to make them well developed cities.
I
I just beat my cultural victory record on King difficulty last night - turn 169, 1100 AD!!
I was shocked when I read this, until I read this:
PS - I found this interesting. Of the 12 CS's in the game, not ONE was Militaristic. They were all maritime or cultural. I had never seen that before, not that I was complaining.
No wonder you got such an amazing victory date! Is there no code to ensure that a more-or-less equal distribution of CS types appear on the map? Needless to say, I look foreword to Thal making the AI more aggressive in CS alliances.
PS I generally play on standard size/speed, emperor or immortal, continents+.
___________________
Original post updated with new stuffs wrt the latest beta releases, ideas and discussion.
gold reserve. The AI will aim for a "target gold" amount to provide a cushion for unexpected events.
to 
, lowering the economic strength variable.
per 
per turn.
on *base* food is more powerful than +2 on defensive buildings and a % on surplus food) and while you did eliminate the +1
