I've just started reading The Highest Frontier, the new Joan Slonczewski book, and after only a couple of chapters, am enjoying the hell out of it. It's just so full of stuff. I mean, I know it's hard sf, and that is what hard sf is meant to be like, but I had forgotten exactly how much I love the way this particular author goes about it. She winds all kinds of social origins and implications into the future tech, which for me helps it to be much more believable.
It's a dense book, I can tell even after two chapters, and I as reader have to be on my toes to catch everything that's flying at me (much like the protagonist and her "toybox" interface).
It's a hardcover, so I'm not carrying it around; it's a treat for me to read at home, and means I'll be prolonging the experience a bit.