What do you do with novels completed en route?
I typically leave newspapers and periodicals in obvious places where other might reuse them (and hopefully not creating trash), e.g. hotel lobby, airport terminal, lounge, restroom, etc.
Books seem, at least to me, a slightly different breed...if I encounter a periodical laying apparently unattended--rather than reporting the object suspicious--I reuse it. However if I encounter an unattended book, I assume someone forgot it and leave it be.