Mount Kilimanjaro is 19,340 feet, and our climb began at around 6,000 feet. We chose the Machame route, which is much more enjoyable and more scenic than the Marangu route, otherwise known as the 'Coca Cola' route. You need time to acclimatize to the elevation, and the slower and less sudden the better. So we took 7 days on the mountain, and if I were to do another attempt I would take either 8 or 9 days on a longer route. The Marangu route is an atrociously short 5 days, and less than 50% success rate of reaching the summit.
For a fantastic reading of my friend Eric Cheng's Kilimanjaro experience, head on over to this link for a good read and some great photographs from his own experience.