Yes, I always have two or three books going at a time, but never of similar genres. The best is a quiet weekend when all I do is do some housework and go back and forth between books throughout the day. I'll either do a fun fantasy or scifi novel alongside nonfiction or literary classic. However, when I really get into a book to the point where I can't put it down at night, then I can only focus on that one until I have reached the ending.