Of the things I would like to see added to GalCiv2, highest on the list would be an added feature to the main menu to pull up the shipyard and design without actually being IN-GAME. I've seen many posts of what X or Y person would like to see made or added, but I'm surprised I haven't found this mentioned yet...
If done right, an open Shipyard would assist in managing custom ships, especially if it was all-tech open. Players could create some nice fully-equipped ships which could be set to come available when all required research was obtained. Even if it was only able to build cosmetic designs without gear, it would enable players to tweak some designs without needing hours of gameplay just to unlock the larger hulls. Just and idea...
(Also, another nice improvement would be the existing in-game shipyard's "Upgrade" feature to leave guns and equipment ON the redesign... It sucks having to re-attach everything when the only upgrade was like a new sensor or a better armor plate, or most INFURIATING, a typo.)