So should I get a SIM with Claro down there, or does AT&T have options for me? I want to be able to use some data, but not a whole lot. Texting is a must and I need probably approx 120min/month. Thanks
You don't say how important cost vs convenience is to your decision. From a cost perspective a local sim will be cheaper in almost all cases but people who call and text you will pay more to reach you so you shift the cost burden to the people who call you.
From a convenience perspective your at&t sim will probably win out. Here is the international section where you can check costs and discount roaming packages: