When cities upgrade could you add another button next to acccept and call it delay or something. This buttton would allow you too delay choosing the city upgrade until you click the turn button again at which point the city upgrade screen would display again. As such you could check your empire and work out what you want to do with the city that upgraded

Currently it is really annoying when a city upgrades and you can't remember what you wanted to do with it and you have to guess if it was going to be a Conclave or a Fortress etc.