I actually didn't like Gleick's other books very much, but Genius is beautiful. I went from thinking I'd major in English to majoring in Physics after reading it back in high school.
And for general sheer amazingness, I always tell people to read Thomas Pynchon's Mason & Dixon. It's like reading Shakespeare; the first 50 pages will take a while, but then you'll get used to the style and realize it's the coolest thing you've ever read.