I read Quantum by Manjit Kumar. He goes back to the days of Einstein and Bohr and explains how they built up their knowledge, so you can follow how quantum theory developed, rather than coming in where we (?they) are now and having what we now know explained, IYSWIM.
Not sure if you're still looking for an accessible book about quantum physics but I loved 'The Quantum Zoo' by Marcus Chown; he wrote it with his wife in mind (so that she could read and understand it) and it's fascinating.
Hanging I read Steven Hawkins years ago, I don't think it's quite what I was looking for but definitely worth another look. Fenouille I'd forgotten The God Particle, definitely one to get again, it was one of the few 'textbook' type books I actually enjoyed. Coke I googled Mr Tompkins, have never heard of the books but I would love to read them, they sound brilliant!
Its probably something you've read already but Steven Hawkings Brief History of Time has a good bit on quarks and the like. I certainly didn't understand it all but it did go some way to explaining the construction of sub-atomic particles and the way they react. This might not be what your're wanting though
DD and I were talking about quantum theory (triggered by reading timeline by Michael Crichton). He actually made it sort of understandable, and she (and I!) would like to know more - she's 14.
Can anyone recommend a book that's vaguely understandable? I've been searching Amazon, and there are quite literally hundreds that seem to be on an 'introductory' level. We're not looking for a textbook for a quantum physics student, more like something that will help us figure out how it all works.