Hi Will:
I'm 100% for it (and for a strong expenditure for environmental cleanup at the same time:
and will spell out why in 125 words or less... but I consider alternative views.
In one of them:
Congressman Barney Frank (D-R.I.) observed aloud on NPR today that a Big Space Program will be paid for by future generations, as the money will be almost all borrowed. Unlike the 1960s, when the national debt was very modest, We the People of the United States of America are already in very, very deep debt before we start talk about spending $100s of billions on space.
His own district has an environmental superfund cleanup site that won't be funded this year, so why do we have money for space exploration?
Another counterpoint: In such national (and international) efforts, we benefit from strong consensus and that means "Democrats" (and others) in space, not just members of the "in" party. A space program will be a strong target in society whose political parties are polarized along lines of "actual fairness" versus "manufactured consent"
And another counterpoint: unmanned space vehicles are less expensive by far, and can do most things that "persons in space" can do -- far more cheaply but just as well. A vast number of well-versed minds have endorsed the option of unmanned space vehicles because they are affordable. Manned missions might squeeze out the funds which might otherwise go to unmanned vehicles.

Why I am for space exploration 100 anyway%:

I love it. I won't oppose a proposal to honestly administer a huge budget for space exploration and manned missions create new
life-support technology and dramas.
Meanwhile, instead of nickeling and diming all our problems, our economic system ought to GET SERIOUS and GET WITH IT and APPLY
what "centuries of experience" has taught us:
about knowing our civil rights
and protecting our freedoms,
housing the homeless,
learning healthy lifestyles,
optimizing the natural environment,
and all-out exploring the universe (including Earth).
I think if space industry jobs are fairly distributed to the whole continuum of Americans (and others)
and SPINOFF benefits are well harvested,
it will pay for itself better than almost any other activity.
Any comments?
Warm regards,
Mike