This operator can help select your international flights, but you'll have to book them yourself help
Fly to/from Kilimanjaro Airport (JRO - Check price) near Arusha. Or fly to/from Arusha Airport (ARK - Check price) via Dar es Salaam or Nairobi (Kenya)
A transfer from and back to the airport is included
Additional accommodation before and at the end of the tour can be arranged for an extra cost
We did a 4-day safari, covering Tarangire, Serengeti, Ngorongoro, and Manyara. I would say that 4 days is more than enough, beyond that it becomes tiring. The guides were always kind and helpful. The lodges booked were always well organized...