I went to Tanzania in 2004 with Thomson Safaris. Tarangire is a favorite for elephants in particular. While off the beaten path, the Rift Valley up through Lake natron is quite different. Lots of great topography and unusual birdlife. We did a hike through Masai villages with our gear on donkeys through Thomson. It is easily one of the most memorable trips I've ever done. I definitely felt as though I had left the world I know and entered something totally different. i'm convinced we were in areas so remote that wee might not have heard about 9/11 for a few days had we been there at that time.