Human rights and civil liberties groups have long lobbied for the closure of Gitmo. I share their concern.
I think the next president should enter into negotiations with the government of Brazil to lease or buy Ilha da Queimada Grande. Another possibility is to swap Gitmo for Queimada Grande. With a bit of remodeling, I'm sure Brazil could turn Gitmo into really nice tourist resort.
Queimada Grande is a far more fitting domicile for captured terrorists like members of ISIS. And it has the added advantage of preparing them for what to expect in the afterlife:
[Last link contains some bad language]