All of the above I completely agree with for multiday Whitney trips, where the start time need be as late as noon, and certainly does not need to be middle of the night.
However, I remain somewhat of two minds about the dayhike option. I believe that the intelligent climber follows an acclimatization schedule. The thing I have trouble with is the night prior to the climb, in which most people are definitely getting an alpine 1-3am start.
I am a strong believer in the power of sleep, and the deleterious effect no sleep has on hiking efficiency, energy, and just feeling good.
I, personally, do not do well when I've not gotten sufficient and high quality sleep.
So, I've taken seriously those who've suggested it is better to go down into town, and get a good (and early!) nights' sleep in prep for the alpine start. I personally have no trouble sleeping on the ground, as soon as it gets dark....but I appreciate that others don't have that gift, and won't get a wink at the Portal, to their detriment.
IF a person has followed an acclimatization schedule, I don't believe that the 8 or so hours in LP will lose anything that they've gained.
Although it does not apply to Whitney, there is a school of thought, most prominently espoused by the great climber Anatoli Boukreev, that on the huge mountains, after following the acclimatization schedule, one should descend WAY down for a night or two, to really saturate the lungs with oxygen, and replenish the body from the harsh environment of extreme altitude. It seemed to work for him, although we are not dealing with "death zone" altitudes on Whitney.
