What's the best itinerary for two weeks in Tanzania?

We are open financially. We are not luxury travelers, but will pay for authenticity above an all-American experience in Africa. There are two of us. 

Arusha   Tanzania   Mt. Kilimanjaro National Park   Kilimanjaro   Ngorongoro   Ngorongoro   Zanzibar   Serengeti   Serengeti National Park