One of our fellow travelers only has one eye, so logically, he only needed a monocular, instead of binoculars. He let me give it a go and I loved it! So much easier to focus and track the animals. I highly recommend it. He said he bought it on Amazon for about $60.
I lost my hair conditioner in Amsterdam, so I spent the entire 12 days in the dry air of Tanzania with hair like straw. You cannot buy normal cosmetics there. I would also bring a rich lotion, eye wash, and saline nasal spray. I have heard of a new product, which is a nasal gel, called Ayr. I haven't tried it yet, but since I live in a dry desert climate, I'm going to find some.
My little insect bite relief stick was a popular item. It immediately stopped the itching and swelling of bug bites. So small and so helpful to have. At the end of the trip, I gifted to one of our drivers. I hope he uses it often.
You definitely want a nice camera. I rented a 400mm lens from LensRentals.com to put on the body of my Canon Rebel and I was so happy with my photos. I was the only one in our group with a "real" camera. I am happy to share all my photos with everyone, but I feel like they missed out on taking their own pictures. Also a lens brush is great for keeping the dust off. Three sets of batteries for each camera worked out just right. One set charging, one set in the camera, and one set in my pocket to reload. Each night I rotated through them.
Lingerie bags (in addition to the cubes) were great for holding smaller items inside the duffle bag. I would bring several with me.
I wish that I had a watch with me. Without my phone, I never knew what time it was. Normally that doesn't bother me, but on this type of tour they are constantly saying, "Meet at 5:30 for breakfast, meet back at the jeeps at 1:30, etc." I was always asking someone what time it was.
I also wish that I had brought warmer clothes. I didn't believe them when they said it was winter there in June and cold. We were at a high elevation and I was much colder than I thought I would be.
Brad's doctor very wisely prescribed Diphen/Atrop (a generic of Lomotil) before we left. I had a very odd illness where waves of nausea would sweep over me and this stopped it within half a hour. It was a life saver for me.