Serengeti or Masai Mara early July
 

Hi,
I am taking my first trip to Africa July 1-18. Ended up getting a flight to Nairobi when initially we had been planning on going to Tanzania only. So now I'm wondering whether we should plan a one-week safari in Kenya followed by a week relaxing where...? Or hop down to Arusha, do the Northern circuit for a week and then go to Zanzibar? I had done a fair amount of research on semi-budget Tanzanian safaris, been in contact with a few operators, etc. Have done no planning for Kenya, but I'm open to whatever it has to offer as well.

Any advice/recommendations/opinions?

The Migration should just about be arriving in the Mara in July (but it always depends on the rains - they can be there in June or as late as end July - one never knows for certain), so your plans should put the Mara at the end of other stops in Kenya. And spend 4/days here, minimum. This, of course, doesn't give you that much time in Kenya if for only a week.

But since you don't have to do the Serengeti in Tanzania, you can manage to do Tarangire (which has a migration between June-Oct) for 2-3/dys, then head to the Ngorongoro Crater where you need 2/nts (1 full day in crater), then head back to Arusha/Kili for a flight to Zanzibar. From Zanzibar you can fly back to NBO for your flight home.

No knowing your budget nor category of accommodations you are considering, I would suggest 10-days in Kenya, 5-days in Tanzania, 3-days Zanzibar, as follows:

Day 1 - Arv NBO
Day 2 - Drive to Amboseli
Day 3 - Amboseli
Day 4 - Fly to NBO, drive to Mountain Lodge (near Mt. Kenya) overnight here for the game at the salt licks at night. This will be a long day, but the flight leaves Amboseli early enough to get you to the Mountain Lodge maybe by 1:30-2pm, so you can have lunch and relax.
Day 5 - Drive to Samburu
Day 6 - Samburu
Day 7 - Fly (you must) to the Mara
Day 8 - Mara
Day 9 - Mara
Day 10 - Mara
Day 11 - Fly to NBO, connect to flight to Arusha/Kili, drive onto Tarangire
Day 12 - Tarangire
Day 13 - Tarangire
Day 14 - Drive to Ngorongoro
Day 15 - Ngorongoro - full day in crater.
Day 16 - Drive to Arusha/Kili - Fly to Zanzibar
Day 17 - Zanzibar
Day 18 - Zanzibar, fly to NBO, connect to flight home.

In some instances you are going to have to fly, as some distances are just too long to drive. As to Zanzibar a lot depends on day of flight/departure times (from Arusha) and return from Zanzibar to NBO. If you have to cut a day, cut 1-day at Tarangire.

Maybe this will work for you.