A big yes to the Sagan books and Dinosaur Heresies
. Now I'll throw out some more (some of these are leaning toward history, but with strong scientific elements):
by Nigel Calder. Very accessible.
The Language Instinct
by Steven Pinker. Very interesting and multidisciplinary.
Mosquito: The Story of Man's Deadliest Foe
by Andrew Spielman and Michael D'Antonio. Yikes! Is that a mosquito on me?!
by Dava Sobel. One of those things you don't think about, but someone had to be the first to get it to work.
Flu: The Story of the Great Influenza Pandemic of 1918 and the Search for the Virus that Caused It
by Gina Kolata. Very timely. My grandmother and her family barely survived it. I grew up hearing stories about it.