Stranger In a Strange Land is my all time favorite book as well, I love the little quirks like how Mike didn't know what laughing was, everyone says it is healthy. I guess that sheds a pretty harsh light on human nature
I did notice however when I read
I Will Fear No Evil that his characters were rather the same, the male leads being all gentlemen bordering on lecherous and the females all being perfect and willing. But he is just so creative with his settings and plots, you can't help but admire him for that.