I would say Los Angeles, CA but since my sister currently lives there, thus being the only redeeming thing about that festering stain on the planet. So my second choice would probably be Lisbon, Portugal. I have nothing against the Portuguese but nuking Portugal is the last thing anyone would ever expect. Granted this would be my decision process with or without terrorists involved as the terrorist would still probably kill me and if they ever got their hands on a nuclear device would likely not put it in the hands of a hostage.