I finished reading 'Tunnel in the Sky' for the second time, and recommending to a friend who is pursuing African American Studies. (I told him the lead character is black, something that was rare in the 1950s, when the book was written). There is also a Zulu girl who 'looks like' the main character's sister.
I still give the book about a 3/5 since it doesn't really have a plot, but there are so many ideas that move the story along, especially since the 'strong' characters are all black...
(Sidenote: The audio book - or at least one I've seen on Amazon - for 'Tunnel in the Sky' has Rod Walker, the lead, depicted as a black kid. It's the 1950's cover that has Rod as white, of course).
Another book I'm looking to read is 'Star Trek'....to prepare for the awesomeness that is 'Star Trek Into Darkness.'