Back in the day on STOnet, I wrote a rather lengthy explantion of how "guild" ships could function. I will attempt to recreate my ideas here.
(Sure Zach, I'd love to hop on board the Devilfish with you, Kinn and Ksuan, as well as the rest of the Hailing Frequency crew! :D )
So, my idea went something like this. Ships would be run in a variety of ways. They could be run by a single player (shuttlecraft, runabouts, small transports, etc.) or could be run by multiple players (Delta Flyer size and up) however for multi-player ships, a system would need to exist where either a human player or an NPC could run the auxillary stations.
So, you join a guild (ship crew) and you gain access to a large ship. So, how would it run? The way I envisioned it, was the Guild Leader would serve as Captain of the vessel, and other guild members would serve the other functions on the ship. The guild would decide on a location to head to, set course and travel to a destination. Once there, the guild would spend some time conducting missions at the chosen location. This would require that missions within STO be written in such a manner that they could be conducted by members of a crew ranging in rank and skill level. (More on that another time) So after the guild spends their time at the location, they move on to a new location. If crew members from a ship are not done at the location the ship was at, they could take a temporary transfer to a starbase near by, or to an allied guild's ship that may be in the area, or simply use a shuttlecraft/runabout from their ship to finish in the sector and then rejoin their ship later.
Now, what happens if there are not enough guild members online at any given time? At that point, NPC crew members could be used to help fulfil the functions of the ship. However, these NPCs would not be useable as crew members for missions or instances / raids type content. If another guild member signs on, they would be able to relieve the NPC who is at their post.
So, what happens when other players want to command ships, but don't want to leave their guild? Simple enough. Once a guild officer reaches the level of Admiral, then multiple captains could exist within the guild, and multiple ships could be assigned to the guild in order to create a "fleet". This allows a guild to grow, without impeding the members who want to continue to advance.
So, how about a person, who doesn't want to be part of a guild, but wants to work with friends and groups? This would be fully possible, however the size of the ship would be limited to best suit the player and limit the reliance on NPC crew members when the person is not operating as part of a group.
I fully believe that player controlled ships and guild ships could be done, and done well within ST:O, following a method such as I have described, and would allow for a very full and immersive experience within the game.