This is probably the best UI Suggestion change I've seen posted so far. I like that look better than current honestly. It gets rid of all that side screen clutter.

Really? It's one of the more thorough and complete set of suggestions I've seen, but that doesn't mean it's good. Some of the suggestions here are objectively bad, like the way it goes to great pains to hide things from the user behind clicks and menus that should be available instantly at a glance without any interaction whatsoever. I'd even go so far as to say that the suggestions for the main world screen and the info/action bars thereof would make the interface even worse than it is currently, which is quite an accomplishment. I mean, there is a reason why the only mod for Civ4 that is considered a "must have" is BUG mod. It's because it adds more information to the UI, not less. Note that it doesn't in any way increase the complexity of the UI, which is what minimalism is supposed to guard against. But minimalism isn't supposed to cripple the UI either.

I'm not sure what the big deal about right-click context menus is either. I mean, certainly, it wouldn't hurt to have them, for people that prefer them. But I literally cannot think of a single strategy game (whether turn-based or realtime, or anything else for that matter) that makes significant use of context menus in its control scheme. And there is a reason for this: Less clicks is generally better, and that one extra right-click to bring the menu open is one extra action that's getting between the user and their goal.

On the other hand, I love the city info screen, the kingdom report, and the champion equip screen. Specifically, I like the way that it brings all the information together on one screen, so that you can see everything you need to at a single glance. I do think that sticking with the heirgamenon format is pretty crippling, because it's such an inefficient way of presenting the information, but that is more of an implementation detail, rather than a problem with the idea behind the suggestion itself. If the current champion info screen and equip screen were combined into what you've got here, that would be fantastic. The two screens are so massively redundant in terms of the information that they display, it's utterly absurd for them to be separated like that. Especially since the equip screen has lovely tooltips telling you just how your stats add up, but the champion info screen, bizarrely, does not. Which brings me onto my next point.

I think the most vital suggestion presented here that should be implemented as a top priority when the UI overhaul comes is: Tooltips! Tooltips everywhere. Everywhere that could conceivably make use of tooltips should have them. It's an excellent way of having information that is available quickly, but without cluttering up the screen in its default state. It is a little silly to think that I currently have to make no less than three clicks to find out what the yield of a resource will be and the cost to build on it.

The most egregious UI error that is not addressed by these suggestions is the way you have to switch back and forth between different tabs in the action bar in order to accomplish different things. That has got to go.

Honestly...just as I started thinking about this thread I realized Elemental would make a sweet mod for Civ V when it comes out.  Use the Civ system for all the units/tech/diplomacy/etc and just convert all the unit types/names and what have you.  Thinking as I type here...I guess you'd lose out on the tactical battles though...a downside. 

Ten Usability Heuristics

by Jakob Nielsen

These are ten general principles for user interface design. They are called "heuristics" because they are more in the nature of rules of thumb than specific usability guidelines.

Visibility of system status

The system should always keep users informed about what is going on, through appropriate feedback within reasonable time.

Match between system and the real world

The system should speak the users' language, with words, phrases and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, making information appear in a natural and logical order.

User control and freedom

Users often choose system functions by mistake and will need a clearly marked "emergency exit" to leave the unwanted state without having to go through an extended dialogue. Support undo and redo.

Consistency and standards

Users should not have to wonder whether different words, situations, or actions mean the same thing. Follow platform conventions.

Error prevention

Even better than good error messages is a careful design which prevents a problem from occurring in the first place. Either eliminate error-prone conditions or check for them and present users with a confirmation option before they commit to the action.

Recognition rather than recall

Minimize the user's memory load by making objects, actions, and options visible. The user should not have to remember information from one part of the dialogue to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate.

Flexibility and efficiency of use

Accelerators -- unseen by the novice user -- may often speed up the interaction for the expert user such that the system can cater to both inexperienced and experienced users. Allow users to tailor frequent actions.

Aesthetic and minimalist design

Dialogues should not contain information which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility.

Help users recognize, diagnose, and recover from errors

Error messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution.

Help and documentation

Even though it is better if the system can be used without documentation, it may be necessary to provide help and documentation. Any such information should be easy to search, focused on the user's task, list concrete steps to be carried out, and not be too large.

Taken from useit.com

Yah, I'm aware it's made with DesktopX. I had a look at it, and I'm not sure it's an ideal choice for a game UI platform, DesktopX is anything but intuitive, but *shrugs*.

Maybe SD can make an XML based UI instead that allows far easier mod access. It is after all how most of the modern MMOs have their UI setup as.