Hello, kindly seeking some input. My 19 year old son and I will be in Buenos Aires for 7 days, 6 nights in early January. We'll be staying at the Park Hyatt and our first priority is to see Buenos Aires in depth. It seems as though we may have time for a side trip as well, possibly 2 days with an overnight. A couple of ideas have emerged, and I'd like some feedback:

Iguazu Falls (obvious attraction)
Tierra del Fuego (bucket list destination)
Mendoza (red wine lovers)

Thoughts? Thanks.