I very much recommend Steve's Plan A suggestion, Francis. When I initially read, "We're first time backpackers, and we haven't hiked in rain and snow so we don't know what to expect.," my immediate reaction was that the west side during the first week of October is not the right place to experience these things for the first time. Taking the same number of days to go up and back on the main trail is a very sound plan. You get to do your own trail recon and you are never more committed than by whatever distance you have hiked.
The route you suggest in your first post is indeed amazing. My daughter and I hiked over New Army Pass and around this past July. But even then, with nearly perfect weather and three nights on the trail from Horseshoe Meadows, we watched three people from a group that left when we did get chopper rides out from Crabtree Meadow Ranger Station. And that was in perfect conditions, with peak daylight and nearly twice as much time to acclimate.
