One of the main issues in most turn based strategy games that causes me to stop playing is that my Empire has grown far too large for me to have any desire to manage. There's currently a proposed Region Capital system that would help to reduce this but even then it may not get rid of just having far too large of an Empire. I propose the ability to create a District. As cities can currently be managed by Prefects (Governors) the ability to assign a skilled officer to take command of a District would further reduce the need to micromanage.
The idea is that the AI would take control of any district you create and you could assign a task to that District. Be it a defensive task, city improvement task, an attack task, or a growth task. The AI would then attempt to complete this task within a time frame and at the end of that time frame it will notify you of its progress so that you can assign either a new task or tell it to continue with the current assigned task.
There should be a risk/reward system implement for Districts. For example an disloyal officer commanding a large district should have the ability to defect or even create there own kingdom. The officer commanding the district should grant bonuses and penalties to that district based on the officers skills. The example being an officer who is a good good administrator but a bad military leader he would; lower revolt risks, increase output of mines and farms, improve build times... This officer would also suffer a penalty in any combat situation, be less likely to successfully complete any military task (perhaps even refusing the request), and other things of this nature.
Districts should have a minimum number of cities before they can be created... Based on the current beta 5 cities at the minimum would probably work with a requirement that the players district never fall below 5 cities. Meaning you could only make a district once you commanded 10 cities. By using Districts in this fashion I can choose to focus on what I please be it a military conquest of a tough bordering enemy or building up a rich agricultural empire in my home sphere of influence.