Where to go from Buenos Aires?

Funny, I own a copy of the Oxford Dictionary of World Geography which includes detailed maps. The color map of South America shows Tierra Del Fuego, but there is no indication of anything called Patagonia. Upon further research, I found Patagonia to be both part of Argentina and Chile. Tierra Dell Fuego is the southernmost tip of South America. And, in my travels, I've been to Brazil, but that was a business trip.