Thanks to all on all the good answers.

Just submitted my lottery form, so hopefully I get something from my 15 choices.

Are the non-reservable campground spots usually full in August? If I can't get a reservation at the family campground, I'll need to crash somewhere to acclimatize up at the portal area.

Actually, I probably should have asked... are the sunsets/sunrises from the Mt Whitney summit great? Although by the look of the trail, anywhere along the rim might be spectacular.

What kind of treatment do you recommend for lake water? I'll take what I think I'll need for the whole trip up and down, but just in case I can take some treatment tablets/filters.