My wife and I just returned from three weeks in Argentina (BA and Mendoza) and Chile (Vina del Mar and Santiago), most of it as part of a food and wine tour. Since we also spend a lot of time every year in Chicago, I have a pretty good perspective on the cities. The previous writers nailed it very well, but (necessarily) in a general way. Yes, Santiago is calmer (and safer), but that doesn't necessarily mean it is boring. Three of the things that we liked best on our trip were Valparaiso, an incredible exhibition of works by the painter Matta that was in progress at the Moneta museum in Santiago, and two (of the three) houses of Pablo Neruda. (Maybe next year we'll go back to see the third house.) They appealed to our interests, but more than likely not to yours.