If you clean off the old one and look very closely at it, you should be able to find its temperature rating stamped into it somewhere. I really think the 160 and 180 are too cold. I'm not sure about whether the 189 or 197 are proper. Someone else can probably suggest the proper one. (The owners manual might even list it.) If you were happy with the way your heater worked in the winter and if the engine never ran too hot, then why not go with the same temp as the old one.

I think there is a bit of a misconception that just because you operate the vehicle in hot climate that you need to go way lower on the thermostadt temp. If you have a clean and healthy cooling system and a properly tuned engine, it should maintain a fairly consistant engine coolant temp whether in Alabama or Alaska.