Okay, so it seems the big problem with closing Gitmo (from what I understand) is what to do with the hardcore assholes whom we know are dangerous yet the evidence we have against them is tainted by 'improper interrogation techniques'.
Let them go.
Indeed, let them go about a hundred yards and have a Marine Corps sniper put a bullet in the backs of their heads*. Got that? It's called pragmatism. I didn't say it's right, or moral, or something we should be proud of, but that's the reality of life ... and death.
And let that be a lesson to us the next time we decide to build a concentration camp.