Two real highlights and one slight disappointment. We did a safari on foot in Lake Nakuru National Park, which I will never forget. We got amazingly close to lots of diverse wildlife, and there really is nothing quite like creeping amongst the trees and suddenly coming face-to-knee with a giraffe! Very knowledgable guides kept us safe, and knew where every single buffalo was before we had even noticed one of them. The second highlight was definitely the Ngorongoro crater. I won't spoil it for you... You just have to experience it for yourself - Comletely mind-blowing! The disappointment was not being able to do the balloon safari in the Serengeti. There's only one company operating balloons, and they only take 32 people per day. So, your chances of doing it are very slim, which isn't clear from the trip notes.
Another really great thing about this trip is the sheer amount of "typical Africa" you see. If you've been put off by the amount of driving described inthe trip notes, then I would encouage you not to worry. There is one 10-hour-ish journey, but there's so much to see and you get an excellent view being so high up in the truck.
Relax and have fun! As soon as you get used to the African pace of life and way of thinking, you'll have a really good time. This is a great way to see Africa, and the opportunities to see wildlife won't disappoint. You get really good views from the truck because it's so high off the ground, which is a big advantage. We saw so many lions, we almost gave up stopping for them! I guarantee you will see some amazing things, and probably not what you expect. The diversity is astonishing, especially travelling through so much countryside.
Do as many of the optional activities as you can. The majority of our group did most of them, which meant they worked out a good bit cheaper and they were mostly excellent. The only things I wouldn't bother with were the snorkelling, and particularly fishing, trips on Zanzibar. These involved far more time travelling on a small wooden boat in choppy waters than time spent snorkelling or fishing, which was a shame. However, as I said, all the other activities were excellent and well organised.
There is a night in Tanga towards the end of the trip. Frankly, Tanga has little to offer tourists, although it is an opportunity to sort out your belongings before heading to Zanzibar. It's a shame this night couldn't be swapped for an extra night in Serengeti as flying from Kilimanjaro airport would avoid the long road journey to Arusha. However, that's a minor quibble and certainly doesn't detract from an otherwise excellent trip.
The time spent on Zanzibar at the end is a great way to relax before returning to the "real world", and the beach hotel in the north has just the right compromise of comfort and relaxed atmosphere. All in all, a highly recommended holiday.