Viajero, is that US$ 110 for 3 nights...? I assume so. If this is the case, its a reasonable deal.
Else, if you are in the range of US$100s per night, the Hilton Buenos Aires has deals for the dates you mention for around US$120+taxes that are good deals... and I imagine the local Starwoods have rates to match.
Cheers
Gaucho