Thanks for reminding me that I need to bust out Kip Thorne's Black Holes & Time Warps
and take another stab at it!
For some reason I just never got around to reading it cover-to-cover, but every now & then I flip through it just to marvel at the wonderful illustrations!
I also love the story about the bet he made with Hawking about whether Cygnus X-1 is a black hole or not.
Another title I like is Fred Alan Wolf's Taking the Quantum Leap