Ringworld

Hmm... I find it somewhat misogynist and I find the MC rather irritating in his garystueness. Sure, that all the females would fall in love with him was part of the story, but it's still unnecessary and stupid.
I like aliens. I can see Khajeet being modeled on Kzits. I like the grasseater aliens. Reminds me of the Kelpiens in Star Trek