Quoting xAshx
An overland truck will save you loads of money, ensure you get to see and do everything and will make solo travel a lot easier as the average truck has about 20 people on it so you can make plenty of friends.
I couldn't disagree more. Africa, especially the eastern and southern parts, are easy enough to travel on your own, providing you have a bit of time and patience. I flicked through a leaflet advertising overland trips about an hour ago and couldn't believe how expensive they were- basically, the cost of an 18-day trip is my entire budget for 2 months. There are, especially in southern Africa, enough hostels and backpackers which means you don't have to be on your own unless you want to. As for seeing the must-see sights- you just end up in the same places as everyone else, with no flexibility at all to do detours/ sidetrips. Sure, it will make life a lot easier, but a true African experience is being crammed into a 16-seater bus with 30 adults, ten kids, six chickens and a goat. Obviously people have different travelling styles, but I think anyone who's done a bit of independent travelling before is certainly able to cope on their own.
Quoting xAshx
Plus there are some of the greatest adventure sports like bunjee jumping the highest jump in the world, white water rafting the falls, cage diving with great white sharks, sandboarding the highest dunes, quad biking through gameparks and the list goes on!
Again, any hostel can book any of these activities for you, and usually for the next day, if you so wish- you don't need an overland company for it. Plus, if you book it by yourself you can always haggle a bit on the price as well 
The only thing you cannot do in Africa- the highest commercial bungy, which is actually in Macao. Otherwise I agree- certainly include Africa on your travel list!