I've been to Tanzania quite a few times - WONDERFUL place!! (I lived in Ethiopia for seven years, so traveled quite extensively in that region.) Ngorongoro is fantastic just about any time of year - absolutely phenomenal. I've also been on safari in Kenya and, while it was wonderful too, I would recommend Ngorongoro over Kenya.

Kilimanjaro really isn't that hard to climb, but don't rush it. Altitude sickness is nothing to play with. My husband got altitude sickness very badly and ws weaving all over - the last mile or so to the summit is along a narrow, icy trail on the rim of the crater. Needless to say, I was pretty nervous. It's a lot better to build one extra day into your climb - much more comfortable that way!! While I haven't been there for a number of years, I'm guessing there are LOTS of tour companies still and you can arrange for the tour right there. It will be MUCH cheaper to wait until you are there to arrange it.

Good luck!! I wish I was going... (I miss Africa so much...)