I've been in one of those 'don't know what to read' moods lately, which always makes me turn to old favorites. I've gone through Heinlein's A Door into Summer (a favorite in my teen years that gets weirder every time I read it), Tanith Lee's Don't Bite the Sun (I have a feeling I only like this because I was young when I first read it) and William Tenn's The Human Angle (no apology for this one; I always forget how good Tenn was until I'm reading him again).