We are planning on going from Arusha to Crater to Central Serengeti to Northern Serengeti and back to Arusha.
One operator that I spoke to strongly advised against doing the safari in this order. She suggested flying from Arusha in the morning to Northern Serengeti and being on a game drive by 10:30 am.
Then on the last day of safari, spending the morning in the Crater and then driving to the airport instead of leaving the Northern Serengeti in the morning and spending the entire day in an airport hotel dayroom waiting for the night flight home.
Her sequence would allow maximum time on game drives. I have to admit that her idea makes a lot of sense to me.