Just completed a 345 turn game on Immense map with Godlike AI. Some thoughts and suggestions.
The UI often makes the game very tedious and some simple enhancements may be very useful.
Larger/better marque for 'Idle Ships' - if you have a lots of ships on a huge map it becomes very difficult to zero in on the ship which is being shown as idle. There is currently a tiny circle in the same colour on the selected ship which is very tough to spot. One has to zoom in and search to find it. The circle highlight should be in a different color and larger too so that it is easily picked out from the maze of ships. This will avoid the need to constantly zoon in and out which believe me gets tedious real fast.
The same is true for planet selection.
If you open a planet you can use the arrow (backward and forward) on the top of the window to go to the next planet. There is no obvious order in which the planets show up. It would be nice if the order was same as in the planet list in the side bar. If the planet is sorted in a particular order it would be nice if the arrow keys follow the same order.
A search facility for ships/planets would be very useful. Today if you have ships in a fleet you cannot find out where a particular ship is (for example some ship which you want to upgrade). If you again have a large number of ships its very difficult and tedious to find one. When the Iconians surrendered their ships I had to spend an hour just locating some of them and decommissioning them. The ship list on the side bar should also have a facility to display by fleet or ship name (at least).
The upgrade window and the colony governor windows are sized such that you cannot read the full name of anything. A mouse over or a right button click which will display details will be useful. Indeed the right button is underused and can be used to good purpose in most screens.
If the planets name have a prefix (of the respective civ) it will again be useful. When a civ surrenders its a massive task to find out all the planets and take effective action.
I discovered that even after I had taken the last planet of the last civ there was no conquest victory. I had to eliminate the starbases and 2 colony ships and only then victory was declared. This is quite amusing but pointless.
There are several such suggestions that I could make but even if Stardock can do the above it will drastically reduce the pain on playing on very large maps.