I agree as we had the same tough choices. Normally my dad always started in Alamosa, since it was the first place we would come upon driving from Ohio, and it was where all the pipe was transfered so one knew roughly when to start.
As you stated, one had tough choices at Chama, but normally chasing a helper engine up the 4% grade to Cumbres won out over heading into the wilds of the line toward Durango. On the last 68 trip we did, we actually started in Durango, chased 478 to Farmington with loads, and empties on the return. Next day 498 to Gato(en route to Chama), and day three saw 3 engines in Chama, and we shot 498 departing with loads for Durango, then we chased the 483 and 493 up the hill, later picking up the helper in Antonito a pacing it to Alamosa.
As you say it would be nice to have to worry about those options today. That was part of the fun of the line for me, as seeing steam, and realizing that any run from 1966 on could be the last one.
Greg