Looking at different itineraries. Most seem to suggest starting in Arusha and traveling generally west and then north through Tarangire, Manyara, NCA and then in to the Serengeti and up to the Mara area. The plan would then be to fly out from there.
At least one other TO suggested doing this in reverse. Fly to Kogatende, then drive back to Arusha visiting the parks in essentially reverse order.
Total time would be around 10-13 days and in late July.
It has been suggested that the benefits of flying in and driving back are that you get exposed to a substantial amount of wildlife immediately and sort of get it out of your system, so that when you move on to the other parks, you can really enjoy what they have to offer (my words, not those of a TO). The other thinking I guess would be to work up to the park that really excites - the Serengeti - and really enjoy how marvelous it is.
I can kind of see benefits to both approaches, but I've never been there.
I would be most appreciative of your thoughts.