Hey RickG,
Your Philmont idea is good. That way they have experience with carrying a backpack mile after mile and day after day so they know what to expect when they sign up.
The reasons ours was 6 days (5 nights) is I wanted a short day getting into Guitar Lake (actually, the tarns above) so we'd be rested and ready for a 2:00 AM departure to see the sunrise from the summit. Then we spent our final night at Lone Pine Lake to recoup in a nice setting and to be in position to hit the Whitney Portal Store for humongous pancakes first thing in the morning (that was a hit!).
A challenge in the planning stage is to get Trail Crest exit permits. When I did it, I called (this was before it went online) 6 months to the day before our entry date and I still had a little difficulty getting the 14 we needed. Back then at least, the rangers had a little discretion and were able to swap-in some slots from other days. Even with that I had to bite my nails until I could get the last 1 or 2 we needed from cancellations later on. There was a thread here on this topic a few weeks ago.
Glenn
