Reddit mentions of A Journey into Gravity and Spacetime ("Scientific American" Library)

I sort of agree with RRC that, really, graduate school is the only place to really learn about this stuff. However, I think the main reason RRC and others are so hesitant to recommend pop-sci books is because so many people read a a pop-sci book, which teaches with analogies and approximations, and then they run with it, espousing a whole lot of nonsense.

However, that being said, pop-sci books do play an important roll in getting people excited about science and thinking "hmm, maybe I want to pursue this." So, here is the book that first excited me about theoretical physics. I would say it is considerably better than any of the Hawking books but it comes with the same warnings, it describes via simplified math and analogies, and they are not to be taken literally or too far.