I had a blast for a couple of weeks in Tanzania and then Zanzibar. Sounds like you're on the same trip, front loaded with South Africa.
A few things that I had that other people in my safari really wish they had:
- a big fat camera with a ridiculous zoom and settings that would allow me to change shutter speed, etc to compensate for taking low level shots at max zoom (I know nothing about cameras but here's the situation. You're going to drive around for 8 hours and your guide is going to spot a leopard in a tree a quarter mile away. You'll be able to see it clearly but at that range it will basically always be blurry because there's no light. You need to know how to manually override your camera to compensate. I figured out how to do this and everybody else in the group just used my pictures. One couple only had a handheld party type camera and couldn't see anything.)
- dramamine. did i mention that you're in a jeep for 8 hours? i meant 14 hours in some cases. sunrise to sundown, especially on travel days in and out of the serengeti. think those jeeps are driving on paved roads? think they have any shocks left? think there's air conditioning? hahahaha. my whole group ran out of dramamine on day2 of the 7 day safari. if you've ever gotten even a little bit of motion sickness, on the teacup ride or whatever, bring your weight in dramamine. also, those stupid sea bracelets. also, the plane ride from tanzania to zanzibar is beautiful, but it's basically shot out of a slingshot. if that's something you need to be medicated for plan ahead.
- re-chargeable batteries for everything that needs it. this kind of goes without saying but you'd be surprised how many people think they can stop up when they get down there.
- if you want to buy local stuff, like tanzanite for example, have it figured out before you get down there and start negotiating with people who swindle tourists for a living.
- massive, ultra-lightweight duffel bags with backpack straps and double fasteners vertically and horizontally. we had a weight limit (40lbs?) for luggage, per person. each of us had a duffel bag we can carry on our back, comfortably, all day that fit all of our stuff. some people brought real luggage which tends to be better at storing than carrying and much less flexible.
- 90 degrees in the daytime, 20 degrees at night. that's your temp range, they aren't gonna have blankets in the jeep for you as you descend ngorongoro at 5am in the dark.
here's what i wish i had:
- solar charging backpack like the one samsonite is selling for $150 right now. i cant even tell you how much this would have saved me in terms of setting up chargers and stuff every night.
- an ipad or some other ereader/tablet device where i could have avoided bringing the 10 books i packed (and left at various places) and i could have uploaded my pictures every night (in case i accidentally erase the sdcard, which incidentally happened after my first day).