Gazebo would like to start progressing onto more substantial changes now that the happiness system is becoming stable. This would include porting over many options from CEP.
With that in mind, these are things that CEP did to tiles and the overall economy that we can consider whether to include or not.
Resource interactions
All improvements, except oil wells, have freshwater/non-freshwater tech improvements (vanilla this is just farms), as well as a regular +1 improvement, so all normal improvements should provide a base of +1 yield initially, +2 on rivers in the mid-game, and +3 yield anywhere by the late game. This would be further improved by policies or any leaders effects, and any yield provided by a resource or building interacting with the resource. (the net effect is to make bonus tiles feel "bonus-y").
Coastlines provide additional food and can provide gold via seaports.
Natural Wonders balanced.
GP Improvements should be balanced (higher yield for customs houses and manufactories than vanilla) and improved by tech and policies.
Strategic resources are more spread out, with fewer (actually zero) 6-8 tile deposits but more 2-3 tile deposits and some deposits of 4. Civs should have a random distribution but be guaranteed some iron and horses. (civs with UUs of horses or iron early on could also get free iron or horses in their capitals).
If yields are increased by this method, we would also want to consider increasing costs. This can be done in a general way assuming the costs of buildings/wonders and units are consistent and regarded as balanced, or the culture costs of policies or tiles is, etc.
Other economic effects to consider
Gold purchasing modifier reduced to make gold buying more viable for buildings. Units, courthouses, and defensive buildings should still be not as cost-effective to rush buy.
City Connection income changed to provide instant income (provides income per route instead of a penalty, but provides less per/population). Instead of a capital modifier included in this income, the capital "trades with itself", which also addresses the railroad capital bug. This tends to reduce the amount of gold provided later on, and slightly increases it early, with a minimal change most of the game.
Villages (trade posts) moved earlier in the game.
Strategic resources revealed before they are connected to trade network, so you can plan for shortages of oil, coal, alum available nearby by whatever means you prefer (war, trade, CS, expansion, etc).
Plantations can be built without clearing jungle, if desired.
Forest chop increased to 40 yield (was much higher). This is in conjunction with yield and cost increases overall.
Merchant specialists provide higher income than other engineers and scientists (3 instead of 2).
Specialist slots re-arranged.
Borders expand faster to natural wonders and resources.
Machu Picchu creates a "super" mountain tile.
Stone Works are unrestricted by plains cities.
University jungle bonus split between University and Lab.
With that in mind, these are things that CEP did to tiles and the overall economy that we can consider whether to include or not.
Resource interactions
All improvements, except oil wells, have freshwater/non-freshwater tech improvements (vanilla this is just farms), as well as a regular +1 improvement, so all normal improvements should provide a base of +1 yield initially, +2 on rivers in the mid-game, and +3 yield anywhere by the late game. This would be further improved by policies or any leaders effects, and any yield provided by a resource or building interacting with the resource. (the net effect is to make bonus tiles feel "bonus-y").
Coastlines provide additional food and can provide gold via seaports.
Natural Wonders balanced.
GP Improvements should be balanced (higher yield for customs houses and manufactories than vanilla) and improved by tech and policies.
Strategic resources are more spread out, with fewer (actually zero) 6-8 tile deposits but more 2-3 tile deposits and some deposits of 4. Civs should have a random distribution but be guaranteed some iron and horses. (civs with UUs of horses or iron early on could also get free iron or horses in their capitals).
If yields are increased by this method, we would also want to consider increasing costs. This can be done in a general way assuming the costs of buildings/wonders and units are consistent and regarded as balanced, or the culture costs of policies or tiles is, etc.
Other economic effects to consider
Gold purchasing modifier reduced to make gold buying more viable for buildings. Units, courthouses, and defensive buildings should still be not as cost-effective to rush buy.
City Connection income changed to provide instant income (provides income per route instead of a penalty, but provides less per/population). Instead of a capital modifier included in this income, the capital "trades with itself", which also addresses the railroad capital bug. This tends to reduce the amount of gold provided later on, and slightly increases it early, with a minimal change most of the game.
Villages (trade posts) moved earlier in the game.
Strategic resources revealed before they are connected to trade network, so you can plan for shortages of oil, coal, alum available nearby by whatever means you prefer (war, trade, CS, expansion, etc).
Plantations can be built without clearing jungle, if desired.
Forest chop increased to 40 yield (was much higher). This is in conjunction with yield and cost increases overall.
Merchant specialists provide higher income than other engineers and scientists (3 instead of 2).
Specialist slots re-arranged.
Borders expand faster to natural wonders and resources.
Machu Picchu creates a "super" mountain tile.
Stone Works are unrestricted by plains cities.
University jungle bonus split between University and Lab.