Ah, for a team-up movie starring various TNG/DS9/VOY characters...
Admiral Jean-Luc Picard,
brought out of semi retirement to oversee the decommission of ENT-E, a partial reunion happens at the ceremony, which is interupted by reports about a tragic event happening to the Titan. He and an available crew go on one last mission to investigate.
First Officier Worf
Security (an all-new character, make it female) 1st Romulan in Starfleet or some such, to butt heads with Worf.
Chief Engineer Miles O'Brien
The Emergency Medical Hologram
Ops/Science Officer Annika "Seven" Hansen
(now an Ensign)
Conn (again, probably a new character)
Major appearances at the film's climax can go to Riker and Troi, when the fate of the Titan is revealed. Cameos for La Forge, B-4 and Beverly Crusher at the start.
Throw in an Andorian appearance, a connection to TOS and all the series' bases are covered in some way.