There is simply no choice in most cases since we're not going to send men to Jupiter, or beyond the solar system for a long time. Unmanned spacecraft, not manned spacecraft has and will pave the way for man to travel through interstellar space. And they can stay in space for decades conducting observations, unlike manned spacecraft can do.
And in many cases man won't have any choice but to send unmanned craft because many of these destinations the environments are simply too extreme or too distant for the technology we currently have.
And for the record, I have been calling for a manned exploration base on the lunar surface and Mars for decades. Relatively close destinations such as these are actually doable.