I moved here in 2002 and met my husband in 2006. While that "sealed the deal" that I would stay here, I already was living in Argentina and considered it my home. I have met a lot of expat women who are only here because of their husbands and kids, many seem to be unhappy. These are generalizations, but if you can´t develop yourself professionally and can´t fit into the culture, it will be frustrating.
I also have another story: an argentine friend of mine married a Spanish woman. He always wanted to move to Europe, and not only found true love but a way to move there. She didn´t like Argentina, but started living here full time. Fast forward four years: the situation in Spain is pretty bad, and now she feels lucky that she can live in Argentina (she is also a scientist and got a good job doing research here). The moral is that things can change. Maybe in five years moving back to the US won´t be appealing or Argentina could be a better choice economically.
No one can tell you what decision is best for you, there are too many factors (do you speak the language? can you work here? do you get along with his family? like the culture? Are you strong and love challenges?). The future is also hard to predict: maybe you get diagnosed with a horrible illness, and free/low cost healthcare in Argentina is a life saver. Maybe you get divorced and your husband says sure, take the kids to the US, but they don´t want to move because Argentina is their home (know of a woman who this happened to).
I agree with PhilipDT that you need to think about your future career. Do you consider your relationship/kids to be your life´s work? OR do you want to develop yourself professionally?
On another note: I´ve met a lot of expat women who fit into this pattern: move to Argentina to be with husband. Hate Argentina, can´t find work in their profession. Get pregnant to have kids to do something with their lives. Get more tied to a country they begin to HATE even more, so have more kids. . .
I love it here. If I got divorced, I would stay here and look for another Argentine man. This doesn´t mean that there are things that I don´t like or find frustrating, but this is my home. I would say it is hard to make your home a place that you don´t like.