Lady of Winterfell
Foxy Lady
It's not typical of the series, being the first one he wrote, of course - IMHO, I'd skip forward a few, and read Mort, or Guards! Guards!.
Is this a series where you can read them out of order? I generally like to try and read a series in the order they were written, but if they don't play off each other, maybe its not that important. Of course, if they're not as good, that would be a good reason to skip as well.
I finished The Universe in a Nutshell. I didn't enjoy it nearly as much as A Briefer History of Time, but it did cover different topics.
Now I'm reading The Dragon Reborn by Robert Jordan. It's been sitting on my shelf for awhile, and I felt I needed to read one of the books that have been sitting around. I'm also reading a book about dark matter and dark energy called Dark Cosmos by Dan Hooper.