Hi! Earlier this year, I was working on a variant to the game using miniatures and dice.
Well, I ended up following that rabbit down a hole which led to a fairly big overhaul, intended to make the board game feel more like the classic Civilization PC versions (CivIII thru CiV, mostly). As well, some of these changes are intended to eliminate the extra gamepieces such as culture and tech cards, which make setup tedious.
One big changes was to develop a fixed tech tree (removing the pyramid-based system) that mimics the tried and true tree from the PC games. However, I created 'Builder' and 'Warmonger' tree branches that are mutually exclusive. So a player has to decide early on if they want to pursue a specific victory while giving some flexibility. However, players may find find themselves picking up some techs from the opposite branch, as the Culture/Space Race/Economic branch contains some valuable techs for growth and quicker research, whereas almost any player will need some basic techs from the Military branch for defense.
In many cases, I also modified the buildings and wonders which affect combat, since I've also eliminated card-based combat.
Another change to speed up production was to allow players to 'buy' units, buildings, and wonders with coins.
Also added three "Project" Wonders to the Space Race, Culture, and Economic wins.
Finally, the other big change was to print and laminate some helpful aids: a smaller culture track, the tech tree, and a new city tracker (with basic rule changes). Laminating the tech tree and culture track means I don't have to use the big fold-out culture tracker or the tech cards, just use a dry-erase marker to mark each. The dry-erase city tracker is also my solution (among the many great solutions proposed here at BGG) to easily track city production.
The city tracker handout also summarizes the new combat system as well.
Warmonger Tech Tree:
"Builder" Tech Tree:
Updated Buildings and rest of the Wonders: