Just left Tanzania, 3 weeks on the The Migration, once your on the Serengeti of the Lenses you note the one thing you may find yourself short on will be Length, the 24-105 + the 70-300 will do the major part of your needs, but you will often find times where you need 500-600, maybe your T1i ?? will do that for you with the 70-300 (I'm not familiar with this Camera but I think it's a 1.6 Crop). What I can tell you is the Serengeti is BIG, huge open spaces, long is needed.
Be very VERY careful of South African Airways if you have flights with this Airline, I had one of my Carry On Bags taken from me at the Door under protest (Flying Business Class) and that's the last I've seen of the Bag, around 10k in Lenses stolen, clearly by the Cabin Staff/Ground Handlers, Dar Es Salam is apparently famous for stolen Camera equipment (As is JoBurg), especially if you are carrying gear in a Hard Case system, do not give up your gear at the door under any circumstances (until now while in South Africa still on Safari SAA are playing dumb, this is an Airline to be avoided if possible).
Dar Es Salam is about as Crappy a place as you could imagine, if your spending 4 days here reconsider, get out into the Serengeti and you will have much more opportunity for producing amazing Images.
Tanzania can be an amazing destination, The Serengeti is a wonderful Photographic opportunity, Dar Es Salam is a place to be avoided other than the requisite entry point, Oh Yes, enjoy the Visa on Arrival system, stand in line with 200 other "Foreigners" waiting to fill in 3 different pieces of Paper, Pay 100 bucks, then look intently for someone holding up your passport as the indicator that it's your turn, speak with an Immigration Person that's partly in the Land of the Dead, then join the line for Immigration Stamping, then attempt to locate your Bags. The Positive to the system is that it prepares you for avoiding Predators with even bigger teeth in the Mara River, they're called Crocodiles with four legs rather than two.
Next year I'm going to see the Migration again, but I'm going to the Masai Mara on the Kenyan side, I hear they're about equivalent to 1960 in terms of Port of Entry to a Major Tourist Attraction, Tanzania is yet to get into the 20th Century, although on reflection I may be overstating, more like 19th.
Other than all that, You will come away with some amazing Images, and unlike myself, hopefully all your Camera Gear Good Luck.