50% of the people who try to summit Whitney will not make it. Among the challenges you need to overcome: the highly restrictive permit application process, physically demanding conditions, extreme weather, dehydration, and if you can overcome all of those things, you never know if acute mountain sickness (altitude sickness) might set in. I am very thankful to have summited last October. We arrived in Lone Pine on a Tuesday night, camped out at the portal the first night (8000'). Be sure to say hello to Doug if you stop at the Portal store, he's one of the good guys. We let the portal at 10 am and ascended to Trail Camp by Wednesday night at 4pm (12,000'). We summited on Thursday (14,505') by leaving at 4:45 am and made the trek all the way down by 7:30 pm. We took Diamox to help with AMS and stayed well-hydrated and loaded with caffeine and ibuprofen. My most difficult time on the mountain came at 10,000 ft, but after making it past that point, I was issue free with the exception of a persistent dull headache while 11,000 ft.
I would HIGHLY recommend planning this trip well in advance, especially if you will be flying to this location. I started planning more than a year in advance. The permits are hard to obtain, and I would hold out for an overnight pass rather than a 24 hour one. Rent a bear canister from the Eastern Sierra Interagency Visitors Center for $5 as they are required gear in the Whitney Zone. I would try to eat as much as possible while climbing in lower altitudes as I have heard AMS makes you lose your appetite, and you'll need the energy. Water sources beyond Trail Camp are scarce to non-existent. Plan on taking 3 liters of water per person to get you up the 97 switchbacks and the final 5 miles to the summit. We got hit with a blizzard near Trail Crest (13,600') but weren't about to turn back. I would also start early from Trail Camp as unpredictable weather can pop up as noon approaches. This was a killer experience, truly extreme, highly rewarding, a great team effort, and provided unrivaled views of the Sierras and beyond. As they say: The summit is optional, the parking lot is mandatory. Be safe and take your time.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.