I had been using a Nikon D80 for many years; but it would not work well for night football because of low max ISO. I just bought a D500 specifically to take pics at high school night football games (as well as daylight soccer games). For night football, I used a Sigma 170-500 zoom, with nominal setting of around 300, and used a monopod (heavy awkward lens to handhold!) What a difference especially with the 10 fps burst mode. No more missed shots of grandson doing placekicking. I shot at Aperture Priority at f6.3, with ISO adjusted manually to allow shutter speeds of at least 1/500 (most shots at 1/1000 or better). Had to keep increasing ISO as it got darker. At ISO 20000, I had a flicker problem--noted by abrupt change in grass color on every other shot in burst mode. Backed off to 12000 and the bad color problem disappeared. This was my first attempt at night football, and had not yet mastered all the features of the D500. With that limited experience, I did get many crisp shots. The D500 is absolutely great for fast moving action.

Been to the places you plan to visit. Take the D500, 200-400, and 24-70. Get a small point-and shoot with optical zoom as a back up (20x zoom). You never know in advance how far the animals will be (up REAL close or 100+ yards away. I used a 28-300 on a D80--that got me 95% of the shot opportunities--most shots in 100-250mm range. (I just bought a D500 to replace it). Missed only a few very long range pic (of rhinos at 300+ yds). Take a set of split/graduated ND filters (essential for some sunrise/sunset shots--maybe other wide angle landscapes too. I took most shots with aperture priority at 5.6 to limit DOF--to emphasize the animal and blur the background. Never change lens in the field--way too much dust. Skip the tripod/monopod and bean bag. Little room on a safari vehicle with 6-8 passengers--and you have to move from side-to-side anyway to get pictures. Next time I would take a 200-600 zoom. In Botswana the drivers can leave marked tracks to get closer to animals; in Kenya and Tanzania drivers must stay on tracks--so there may be more long shots. Have a great trip.

I was in Kenya in June 2016. Local winter, so temps rarely got above 80, lows in 50s. In western Kenya (Masa Mara region), you are above 3000 ft, so it gets cold at night (and at beginning of early morning game drive). Plan to dress in "layers" and shed as day warms up. Rainy season just ended, so bush was still green, but getting dry. Moderate dust an annoyance, so keep cameras covered as others cite. I used Nikon with 55-300 tele. Great for 95% of shots. Need 500/600 for some shots--that I could not get with the 300. I carried a small "back-up" point and shoot that got down to 25 mm for close ups and wide angles (e.g. lions walking past the vehicle 6 feet away). Take 3 rechargeable batteries for each camera; can't count on electricity in some places. Also bring voltage converter, since local juice is 220/240 volts. A set of split neutral density filters is essential for the sunrise/sunset shots--spectacular views!! I plan to return in 2 years--Serengeti region in Kenya/Tanzania.

I have been on 2 safaris. Great photo ops in all countries, but ops strongly depend on experience of the tour company and the local guide/driver. I used Nikon D80 with 55-300mm zoom and a Panasonic ZS6 (25mm w/12.5 optical zoom). Used the Panasonic to gain back the wide angle I gave up with the Nikon 55-300 and as a back up. The 300 zoom is OK for 90% of the shots, but you need a 500/600 reach for some shots (e.g. rhinos, not common to see and very skittish). A 150-600 zoom is very heavy and awkward (rented one to take pics of grandsons soccer game from the stands. You need a mono-pod to comfortably hold that). It would be OK for a safari, since many shots are made with vehicle stopped and you could also support the camera/lens with a bag/cushion. Don't even think about changing a lens during the game drive--very dusty!!!. My daughter had a high-end point/shoot with a 25X optical zoom. She got long-range shots that I could not. Bottom line:
1. have a long-range capability for those "once in a lifetime shots"
2. carry a back up with wide angle and tele capability (at least 25x, 40 is better)
3. never change lens in the vehicle
4. carry plastic baggies to cover the camera from rain/spray/dust
5. carry at least 3 batteries for each camera. Bring a voltage converter with you, so you can use your 115 volt charger on the local 220 volt outlets.