One thing I've been thinking about recently is how the influence amount from gifts to city-states doesn't decay over the eras. 1000g during the Classical era is a significantly larger investment than 1000g during the Atomic era. In late game, it tends to become trivial to buy up all the city-states if you so desire. It seems to me that either the amount of gold to buy city-state influence should go up by era or the amount of influence you get should go down (or a combination of both). This would also significantly increase the value of completing a city-state's quests, which by late game I usually just ignore. I wanted to see if other people felt similarly.