Our plan was simple, to see more of Africa, with limited funds, and while maximising our chance of seeing the Big 5 and the Gorillas. Using a tour company like Absolute Africa really helped us with planning and budgetting this trip so early on in our travelling lives. I also think for such a long overland trip like this, staying in rough and ready accomodation it help to be young.
NOTES: We booked a cheap group safari with the lodge we stayed at. We knew that we would be paired up with at least 4 other travellers to make the tour viable. Also failing that that we would be able to split the amount and pay slightly extra each per head to ensure that it went ahead. The vehicel arranged for us was a 4x4 Toyota Hiace with pop top roof. Our driver was very friendly and skilled and managed to get the vehicle up paths you'd expect a land cruiser to make.
NOTES: The Masai Mara National Park is a smaller reserve than some of its neighbours, but it still contains the big 5 and some argue having a smaller area makes it easier to conserve and also find the animals. On the downside it can seem overwhelmingly busy due to the number of vehicles and tourists in such a small space. If you are lucky you might be one of the first at an animal spotting before the whole park has been radioed in and arrived. That way you can leave before you get boxed in.
NOTES: You definitely attract more attention in Mwanza's traffic, especially being in a big yellow tourist truck. Additionally it is very cold overnight up on the edge and on a morning game drive in the Ngorongoro Crater area (due to the altitude). Finally Zanzibar has very conservative views and especially in the main town tourists should take care to remain safe and covered up. Acid attacks have taken place here against westerners deemed to not be respecting local culture and ways.
This is a budget way to do Africa and especially safari's. I'd recommend adding on a safari as you are limited in where you can go and also how close the animals will come when you are in a huge converted hgv (yellow big truck). With a tour like this you'll be camping in tents mostly and cooking as a group for yourselves.
You can see how our actual trip went along with photos here: Kenya 2011