I've read nearly every book Heinlein ever wrote before "The Cat Who Walks Through Walls". My favorites are "Starship Troopers", "The Puppet Masters", and "Starman Jones". "Have Space Suit Will Travel" was alright. I'm reading the "Lensman" series straight through right now for the first time. I've read a quantity of Azimov's books. My absolute all time favorite book by him is "Azimov's Mysteries". They are so clever and scientifically based. "I, Robot" was pretty interesting as well, and I've read "Fantastic Voyage" a long time ago. I've read every single one of Douglas Adams' "Hitchiker" series. The first one's got to be the best. Favorite of all time? Hmm... ever read "The Icarus Hunt" by Timothy Zahn? I love it. My favorite's got to be either that or "Manta's Gift" by the same author. Probably "Manta's Gift": it's even more original. Never read "The Moon is a Harsh Mistress", another one to add to my list of required reading. =)