This is where you should go for your first trip to Africa. Advice given to someone who doesn't know much about the place but is curious enough to visit.
"Excellent you are considering visiting a vast and amazing place. The big challenge is deciding where to go. With 50 odd countries each with different offerings, choosing can be quite hard. Let's start with the most basic idea of what people like you think Africa is. Safaris and animals come to mind. So Kenya, Tanzania, South Africa, Botswana are great starters. But of course there has to be more. There is.
Enjoy beaches? The coastal towns of Lamu, Malindi, Cape Town, and Ponta Mamoli will get you hooked forever; so will the blissful islands of Mauritius and Seychelles. Fancy the desert? Go to Botswana and Namibia. But be warned, that if you want to see nature and uncivilized natives, avoid cities like Nairobi, Luanda, Johannesburg, Addis, and Lagos. You will not find them there; except maybe in a city zoo or the pranksters pretending to be masaai warriors, who'll make you to jump and chant with them as you make a fool of yourself. Warlords, orphans, wildlife, and geriatric autocrats are there if that's what you want to see.
The cities are just like any other modern city. Characterless glass buildings and bums everywhere, loads of bums. Income inequality on live display. They are boring for a first time guest who wants to see natives, animals and land, Hemingway style. And very exciting, maybe even deadly, for those with a thrill for speed and surprise heart attacks induced by demonic cab drivers. Speed limits are optional, and the natives know how cross without crosswalks, and avoid instant death by mere inches.
Although Nairobi has an animal park right next to the city, unless you're an expat do not stay there longer than it requires to catch the helicopter ride to the Mara. A pith helmet and khakis with military style jacket is standard to bask in the colonial spirit. Don't forget selfies at the Karen Blixen farm as you enjoy breakfast with giraffes, finished off with a trip to an orphanage 15 minutes away. Or just yank the nearest child from their dead mother for the forced selfie. But few travel thousands of miles to snap awkward selfies with orphans, whose names you forget after 5 minutes, so that wouldn't make sense for you, a person of money. So grab coffee with the brilliant yet underfunded techprenuers in Lagos, Johannesburg, Nairobi and see what they are up to.
In the North, Egypt, Morocco, and Tunisia (a great democracy by the way) are okay. The Arab world is very different to that of Sub Sahara Africa. Did you say you enjoy a bit of risk? If you do, may I suggest Chad, Mali, Niger, Libya, Mogadishu, C.A.R, South Sudan, and maybe the southern Algeria border crossing for excellent tea with Kalashnikovs and refugee smugglers? If you find yourself on some type of watch list though, accuse the State Department of having a high risk travel advisory for the entire continent. Argue they're exaggerating the risks and that you know better than they do. They'll leave you alone. You're a pro. Even if you have no fucking clue what you're doing. Which is most visitors anyway.
You said your friend speaks Russian and has a taste for diamonds. If she comes, she'll step off on a red carpet in C.A.R, and if her Russian is convincing enough, will be driven in black armored SUVs as an "advisor" with bogus rights to a mineral mine. If she's smarter, she would sell her spoils to a revered Sudanese General for a quick profit. I hear most of his troops are fighting some ghastly war in Yemen, leaving him a bit undermanned for the bloody diamond business. She'll be helping an African out.
You speak French? West Africa is the place. The beaches in Senegal and Nigeria are gorgeous. Their historical forts are not. You'll find shackles and brutal artifacts from the slave trade. Moving exhibitions, a bit much for the first trip. Congo is great. Angola is okay (don't build an economy on oil). You'll enjoy high speed internet on the autocratic paradise of Rwanda. First to implement 5G. Uganda's beautiful lush hills will suck your breath away. Ethiopia is simply on another planet.
Now where will you go?