recommendations?

1) spend some time in the Crater Highlands, Empakai Crater, Lake Natron, Oldoinyo Lengai; then down to Lake Eyasi, you can visit the Hadzabe and go hunting with them.

2) visit Tarangire National Park (very beautiful, in my opinion) and Lake Manyara National Park; end up in Arusha National Park for a cool hiking safari.

3) head south to Selous Game Reserve, a much less crowded option with stunning river views.

I took a similar trip in September, but I started in Zanzibar and worked my way north. I had some extra time in the north and ended up doing a 5-day cultural tour based out of Arusha. These tours can be arranged through TTB, but I would strongly recommend a local guide, Moshi Changai (www.tanzaniaculturaltours.com). Moshi was born and raised in the Kondoa region just south of Arusha, so is very knowledgeable and has lots of connections everywhere he goes. As a single, female traveller, I was hesitant to venture out on my own, but Moshi was very trustworthy and provided me with the experience of a lifetime. Cultural tours offer a great opportunity to experience the non-touristy side of Tanzania. It was the highlight of my trip.

You could also go to Lushoto in the Usambara mountains for a few days. Beautiful scenery, friendly people and easy hill walking.