Harder than Whitney? Not for us. Having many Whitney summits between the three of us we all agreed Langley via Army Pass on a clear, beautiful day is much easier than Whitney. Our opinion, your mileage may vary.
Awesome comeback DUG! Man... 40+ miles in a day that takes a serious mental determination, I'm sure your body will follow suit soon enough and you'll be cranking harder (than I ever will) in short order.
I also definitely agree that a clear sunny day can make the difference on Langley, and friend of mine did Langley in late August during one of the big thunder squalls that hit the East Side this summer. The trail is cake but hiking soaked and cold (in non-stop hail for 2+ hours) ratcheted up the suck-factor by a few standard deviations. I would've rather been on the MWMT during that storm (or not in the storm, period).
