I have always thought that carriers would be a good idea to implement, although choosing how is complicated enough in and of itself. Though the warp bubble can let you make a makeshift carrier, there is plenty of room for improvement.
The main point of a carrier is launching short-ranged fighters from a long-ranged navy. In GalCiv2, it slowly becomes essential that your ships have the speed and range to reach the enemy, while still having the firepower to engage them. Tiny and Small hulls cannot effectively do this, and they seem to become obsolete not too long after the medium hull is unlocked. What I believe should be implemented for carriers is two things :
1.) Carrier modules that would increase the logistical cost of the ship equipped with one, but would allow it to tow a limited number of ships. This could be used with hyperdrive-free vessels (below), or with vessels that lack in the life-support needed to reach a certain area. This means that carriers could be giant tugs for slow or short-ranged ships.
2.) Mini, Tiny, Small, and Medium-sized hulls that start with no base speed or life-support but extra space and a cheaper hull. If the carrier was lost, these ships would float in space until destroyed, picked up, or (based on size and life-support tech) lost some critical system and became derelict. Therefore these hulls would be useful since they would be superior to normal models and could fight either above planet or with a carrier; yet at the same time they would be risky, since they require a carrier to move at all.
I do not want fighters to have some kind of maneuverability bonus - if modern weapons have pinpoint accuracy in an atmosphere and we are already making pinpoint-accurate lasers, I don't think that dodging weapons-fire would be realistic hundreds of years later in the vacuum of space. Additionally, carriers should have the disadvantage of being either unable to hold many ships, or needing to be very large to support both weaponry and the hanger.
To respond to a few criticisms:
WhoStoleMyNickName: Although I agree with much of your post, I don't equate tiny and small hulls with triremes and cogs; rather, I equate them with gunboats and corvettes in a navy of cruisers and battleships (since in space, aircraft carriers as they are now have no real place). What I want is to be able to make those gunboats and corvettes fill the roll of fighters and bombers since as GalCiv2 has it now, all you really have are just the biggest ship you can afford to mass-produce filling your ranks, with larger ships acting in more critical areas. And yes, I know no modern navy uses gunboat-carriers or corvette-carriers, but remember that aircraft carriers and submarines dominate modern naval theory.
No one in particular: I like the idea of fighters as a weapon module, but I want something more than just a Homeworld Drone Frigate.
To sum up what I have said since this post is long: carriers could use extra logistics, ships without hyperdrives can be used with carriers to allow for more focus on weapons, and fighters do not get unrealistic maneuverability bonuses. I also understand that balancing makes this far more complicated than this summary allows.