When I'm pondering whether to produce e.g. a lumber mill, it's not easy to see which tiles would be affected. Forest can look a lot like wetland and palm trees if there's a district on top of it, so there's no easy visual way to see where I will benefit from a given improvement that affects only some types of tiles. Right now I have to mouse over every tile to check its type, which gets boring fast.



My suggestion is that when I mouse over the improvement under the available constructions, all affected tiles in the region are highlighted so I can easily see how much of a boost I'll get, both for current and potential district tiles.