1. Where to acclimatize

For camping, I agree with Horseshoe Meadows (10,000') or Onion Valley (9,600'). Onion Valley gives you a wonderful opportunity to acclimatize by climbing up to Kearsarge Pass (11,760') or just hanging out at one of the lakes between the trailhead and the pass. Personally, I think it would be a bit aggressive, if staying at Horseshoe Meadows, to go for Langley or Cirque; if it were me, I'd go hang out in the Cottonwood Lakes Basin, maybe even get a fishing permit.... (For photos of the area, see the trip report I posted yesterday). I stayed at OV for two nights before my first Whitney Climb in 2010.

If you don't want to camp, consider high altitude lodging like the Rock Creek Lodge, which is near 10,000 feet. Really fantastic acclimatizing hikes nearby out of Mosquito Flat trailhead. They have relatively reasonably priced cabins (the cheaper ones being more rustic but at least having a kitchen, though shared bath). I stayed at Rock Creek Lodge for two nights before my second Whitney Climb in 2011.

2. Diamox

This can help, but like others said, test it out at home first. And avoid the glaucoma dose of, what, 250mg 2x a day, that some doctors ignorantly prescribe for altitude. Caveat: I am no doctor (others here are), but generally, the recommendation seems to be no more than 125 mg twice a day for a male. I am female and, when I take Diamox (which is increasingly rarely now), I take just 62.5mg before bed (Diamox does some of its best work when you are sleeping and not consciously breathing or working).

3. Other

Hydration is important, and flying can dehydrate you. While you don't want to overdo the water intake, you do want to arrive in California well-hydrated, which is especially important because of your flying. For myself, I try to drink at least 1 gallon of water the day before I go to altitude, and I lay off the diuretics at altitude (which means no caffeine).

Also, I take electrolyte supplements at altitude. I find that, for the first few days I am at altitude, I tend to pee more, with or without Diamox in my system. Electrolytes can be very important.