Xconq is best with a window-style interface, either tiled or overlapping. Overlapping is more flexible, but also more complicated for players. In the following discussion, "window" will refer to a logically unified part of the display, which can be either a distinct window or merely a panel embedded in some larger window.
The centerpiece window should be a map display. This will be the most-used window, since it will typically display more useful information than any other window. This means that it must also exhibit very good performance.
When a game starts up, the map display should be centered on one of the player's units, preferably one close to the center of all the player's units.
Another recommended window is a list of all the sides and where they stand in both the current turn and in the game as a whole. Each side's entry should include its name, a progress bar or other doneness indicator, and room for all the scores and scorekeepers that apply to that side.
If possible, you should also implement some kind of "face" or group of faces/expressions for a side, so get a barbarian's face to repn a side instead of generic. Could have interface generate remarks/balloons if face clicked on, perhaps a reason for feelings, slogan, citation of agreement or broken agreement, etc. Need 5 faces for hostile, unfavorable, neutral, favorable, friendly/trusting.
Since the rules for when sides are in or out of a game can be complicated, it is important to indicate each side's status clearly. The most important bit is the in or out part. You should indicate sides that are out of the game by dimming or graying, and by removing any indicators of game play, such as the side's progress display. Keep in mind that you may need to list the sides before or after the actual game.
To indicate that a side lost, you can draw a line through it. To indicate that it won, you can draw laurels or other decoration all around.
The action progress bar for each side tells all the players about how turn is progressing, and should reflect the aggregate of unit states. Here are some suggested appearances:
Technically, the progress bars for other sides gives away information about how strong they are and what they're doing. However, the interface benefit of players knowing how fast each of them is moving and when the turn is likely to be over is tremendous.