"Your families aren't safe." They weren't before Guantanamo Bay closed. Osama Bin Laden is still out there.
"You're going to supply the terrorists with fresh new faces with a vendetta against the U.S." Our foreign policy of simply supporting Israel with money and weapons, of fighting in the borders of Afghanistan/Pakistan, incurring civilian casualties when we launch military strikes in Iraq -- all occupational hazards of fighting wars, we create new recruits for terror camps. They didn't like us before. We've been doing all the things that made 'em hate us from the get go - both right and wrong - for a long time.
Closing Gitmo was the right thing to do. You can't continue to defend who you are and what makes you great (liberty, justice, and civil rights) while running a place like Guantanamo Bay.