In 2021, we did five days at the Masai Mara in Kenya, four days in Serengeti National Park in Tanzania, three days at Kilimanjaro, and then we flew down to Victoria Falls for four days and finished in Cape Town (which was cut short because of a covid lockdown).
Let me tell you--that was a lot. Traveling from Nairobi to Cape Town is akin to New York to Los Angeles. But I have a lot of thoughts and recommendations if you want to go that route.
I also did Egypt back in 2008. I'm not sure I would do it right now, with the war in Israel. But I'm not sure I wouldn't. It's not like there's every a real good time to do Egypt.
I've stopped in Tunisia and Morocco on a cruise back in the mid-naughts, so my experience in those countries is pretty limited. Morocco was really cool. Tunisia has the ruins of Roman Carthage (they did a really good job of destroying Carthaginian Carthage--there's not much to see from before the Third Punic War). But I'm not sure I'd go out of my way for that unless you're just a huge Roman history buff.
As to real highlights, I'd say the African selection of cities is somewhat lacking. Cairo and Cape Town are pretty great. Otherwise, . . . meh. Natural wonders--Victoria Falls was amazing. Kilimanjaro is somewhat disappointing in that the summit is typically in the clouds; but at the same time it's easy to go up. On the safari end, I'd do the Masai Mara over Serengeti. On the cultural front, if you're at a safari lodge, they'll always offer a trek over to a nearby village, which is pretty interesting.
So anyway--I'm happy to answer any questions you have as you get to a more refined thought on an itinerary.
Also, I would strongly recommend a travel agent. Africa is the only place I'd use a travel agent, but I think there it's almost essential. I have a good recommendation if you get down to needing one.