I also agree MoM's UI is now very dated. I'd look to more recent 4X games for examples of what UIs worked.
One feature that hasn't been mentioned yet is historical graphs and other feedback about which players are doing better and in which areas. Lots of variation possible there. Some games have given periodic reports but not provided an on-demand menu. Some games show the current leaders in a few categories but don't provide historical graphs.
One feature that wasn't in MoM that is more common today is unit promotions. Personally, I hate them. Not sure why. Perhaps a feeling that I can never remember the tree and a feeling that promotions greatly increase the micromanagement by effectively multiplying the types of available units. (BTW, why do games display the tech tree when picking research but don't display the promotion tree when picking promotions?)
Another vote for customizable grand viziers and an ability to say which cities are managed by which vizier.
---------- Post added at 11:23 AM ---------- Previous post was at 11:15 AM ----------
Of course the number one peeve for MoM is also the number one favorite feature! A seemingly unbalanced system with over the top awe and shock.
The point was that there were *multiple* killer strategies. My favorite was the invisible flying warships. Flight allowed them to leave the seas and venture onto land where they were unbalanced.
Over the top spells and units (or more likely a clever combination of them) are fun. As long as *all* of the players have some way of delivering awe and shock, the system can still be "fair". It's best if there's some sort of counter for everything though. The problem that MoM had was that the AI wasn't smart enough to make use of the killer combinations and the AI wasn't smart enough to be able to counter them.
---------- Post added at 11:56 AM ---------- Previous post was at 11:23 AM ----------
Another thing to avoid in WoM (even if it's not something that was in MoM)...
Don't make things hard to understand or close off choices too soon. I recently looked at the master of mana mod for civ iv. Right on the first turn, I find that I can customize my city into one of three guilds. With no good documentation or feedback about the choices. Yuck. A better game design would be to push those building choices deeper into the city or research trees so that they player would have to be several turns into the game and probably have multiple cities before making important irrevocable choices. This helps keep the learning curve easier. A similar mechanic in Fallen Enchantress didn't feel ugly. But FE had a built-in delay before you made that choice the first time and made it very easy to understand the differences.