If the times can be made to fit in, the associated coach service between Fort William and Oban follows a scenic route along the east side of Loch Linnhe. It's run by West Coast Motors under the Citylink brand, and when I used the afternoon northbound service some years ago, there weren't more than about 20 passengers on board at any one time - about a dozen of us went from end to end. I used it for a triangular journey Fort Bill -> Crianlarich -> Oban -> Fort Bill which was an excellent day trip, though I'm not sure whether that still works on current timetables. If there isn't time to do both, though, I would do the full West Highland line experience in preference to the coach.
