Um, I'd say, try a smattering of different authors. Pick up Heinlein's Double Star or Starship Troopers. Connie Willis - Doomsday Book (depressing but really good) or To Say Nothing of the Dog. Or both. Dune, if you haven't read it. Asimov's Foundation series, but not Foundation's Edge or Foundation and Earth, IMO. Any of Arthur Clarke's short stories. Ender's Game by Orson Scott Card. Code of the Lifemaker, James Hogan.
I could go on...
Thanks, but summer is only three months. That's a good list to work from.
And, like I said about "The Left Behind" series. I know, I know. But it's kinda like my trashy beach novel substitute...