katrina, the advice above is good. Regarding Diamox -- you need a prescription from a doctor. I've always used the minimum dose: half a 125 mg tablet twice a day, starting the morning before the hike to Trail Camp. I always sleep one night at 10,000' elevation Horseshoe Meadows before heading up the trail.

Your 3 days in Lone Pine give you the opportunity to head up to Horseshoe Meadows and hike around. Two days before, maybe hike all the way to Cottonwood Lakes and back. The day before, do the shorter hike to Trail Peak, south west of HM. By spending those two days at and above 10k, everyone should get a decent level of acclimatization. It's the people who drive from their low-elevation home directly to Whitney Portal and then hike up to Trail Camp all in the same day are the ones who wake up the next day with headaches and nausea.