I agree with Matthew K that the Machame route is the way to go, but think that 5 or 6 days is plenty of time to acclimatize. Until the summit day, I found Kili far easier than Whitney. Why? On Kili, you have porters carrying all your gear, the food is great and plentiful and you only do about 2,000 vertical per day (until the summit day). Summit day on Kili, however, dwarfs anything I've ever experienced on Whitney. You start at ~12,500 early in the morning and do a slow climb up to high camp at 15,500. There, you have dinner (however, the high altitude kills most folk's appetites), pack your summit pack and try to get a couple of hours of sleep (impossible). At around midnight or so, you start a slow (pole pole) climb up to the summit at ~19,700, take a few pics and then back to high camp arriving around 11 am. On the 5 day trip, we rested and ate a little, then headed down to 10,500. When I arrived at high camp from the summit, I thought that there was no way I would ever make another 5-6 hours of down climbing. However, with the loss of altitude it was far easier than I expected. So summit day is basically 30 hours long going from 12,500 to 19,700 and back down to 10,500. Even with just a light summit pack, it far exceeds even a one day trip up and down Whitney. By the most common tourist routes Kili is just a walk-up (there are many very challenging technical routes up Kili) and no more difficult than Whitney. Whitney would make a great training climb for Kili.