A steel beam properly sized for the header might give you the most room for the door in comparison to wood.
Speaking of how the door opens.. I have about a 9.5' tall doorway and an 18' ceiling, had the door installed so it runs up the wall and turns at the ceiling, gives plenty of inside height even with door open. Here's a picture you can just see the track in the corner.
https://picasaweb.google.com/118082...sionProgressPictures#5795541210979156226Grigg