I'm sure this has been suggested but once you have a certain amount of resources, you spend more time managing them than anything else. So my two cents:

Need a high level screen showing status of each system you own. Do I have someone in my system, not passing through but orbiting something.
High level screen to show systems that I'm monitoring
High level screen showing where my resources are going and how much each one is getting.
High level screen showing where all my ships are going and how long before they arrive, I don't know how many times I built extra ships because I couldn't tell where anything was going.
Sort ships on the ships screen by all the different ways so I can find a ship
Sort people on the diplomacy screen so I can actually find someone

Good luck getting them all in but they are well needed with the complexity of a game like this.