Much can depend on how you view a book. Some of Heinleins stuff is pretty sad. 'The Moon is a Harsh Mistress' often impacts me. Rather strange as a 12 year old girl dies and I feel nothing, but I 'morn' the death of a non-human.
I find 'Brave New World' much sadder than 1984. Like many books 'Brave New World' gets its title from a line of dialog in the book. Something like 'What a brave new world with such beautiful people in it'. To me the fall from such hope is much sadder than the grim world of 1984.