[ I've been away from GalCiv for a while, so foregive me if this is already in place (I doubt it). ]
Right now GalCiv has a uniform space travel model: ships travel at constant velocity (eventually faster and faster). The game would gain a very interesting dimension if this changed over time( as a result of research) like this:
1) Constant velocity (like today)
2) Constant acceleration. You define ships' destination and the computer calculates the time to accelerate and decelerate. This travel becomes faster but you cannot stop in the middle of a multi-turn trip. Battles are limited to a single salvo (or, in a finer model, a calculated series of salvos).
3) The wormhole age:
a) planet-to-planet wormholes that allow for instant transfer of population and goods between planets. It should give significant kick to the local economies, with the $ and manufacturing improvement being a product of a formula that takes into account the productivity of other planets in the wormhole network, i.e. first 2 planets connected both help each other, but when a third one gets a wormhole, things improve for all three again. Population happiness should be evened out as well (proportionally to the populations) due to free migration. Research could improve wormhole "throughput" and thus its influence on the economy and such

orbital wormholes (and eventually station wormholes) transfer ships instantly between themselves. Chaining multiple jumps of such nature would require extra research. Eventually wormhole-endpoint ships appear (wormhole gates propelled by regular drives, no self-jumping capability yet.
c) orbital (and starbase) wormholes/farcasters will transfer a ship instantly to any point in space withing a certain radius. From there on the ship has to use its own drives. With extra research farcaster ships appear: their only function is to "farcast" other ships.
d) wormhole engines: a ship with such moves in a series of instant jumps. Initially the jumps could be of fixed size, thus requiring to have both new and conventional drives on the same ship. Jumping over enemy fleets will be fun!
Global events could include "warp storms" making wormhole travel impossible, or (more fun!) unpredictable (and messing up the dependent economies for a while).
Fill up the list of Galactic Wonders with your own ideas

If these Eras of star travel are implemented, there will be a delightful variation in the gameplay.
I am sure the creative folks at Stardock can fill up the details, and if not, my fellow players will pitch in.
Have fun!
A>