I haven't generally found that many "Africa-wide" volumes that I like on this topic. I do like Jonathan Reynolds new, short, cheap, Sovereignty and Struggle: Africa and Africans in the Era of the Cold War, 1945-1994. It's very very accessible and does some good social and cultural work as well as covering political/economic transitions. For older volumes, I like Basil Davidson's Modern Africa: A Social and Political History, but that's partly because the old guy was an incredible activist, partisan, journalist, and first-hand chronicler of a continent in transition. There is of course the classic UNESCO General History of Africa. Vol. VIII, edited by Ali Mazrui, has some great chapters. It is, however, more divided by theme and region than one might want if you're looking for a synthesis. I find David Birmingham's Decolonization of Africa to be dry, one-thing-after-another history and not really an 'interpretation'. Fred Cooper's Africa since 1800, on the other hand, is a superior analysis, but somewhat textbook-y in some ways.