I flew to Tanzania on Northwest/KLM. For them, you need about 90,000 miles for a flight from the U.S. to Africa. For cheapest flights, try a number of different airports to depart and arrive; usually going from New York is cheapest, and sometimes going to the Kilimanjaro or Dar es Salaam airports are cheaper than flying into Nairobi, though you'd have to take a long bus ride to get from Dar to Nairobi...PM me if you want more info on travel in Africa!