I didn't care for that civ 5 mechanic, at times it was nice, but most times it distracted me from my current goal I was trying to do. I'd end up fortifying all my units just so I could end my turn when I wanted to end my turn.
Each character that has movement points is lit up with a green outline and the cities as you pointed out have the zzz... attached to them. If you turn on autoturn it will automatically end your turn when all your units and cities are doing something and so it is exactly the request you are asking for in the current game.