Casa Sur is a really good, reasonable alternative to the grand hotels of Recoleta, the Alvear, Park Hyatt, Mansion Algodon and Four Seasons.  Located on Avenida Callao just down the street from the big boys in a pretty 10-story house, this small boutique hotel has decently sized, peacefully decorated rooms, good service, an in-house restaurant, a tiny spa and, best of all, this great location.  The rates are half those of the others and, while the entry level executive room might feel tight for two, there are other categories upwards from there.  Regardless of the category, however, all rooms are well designed, contain everything one needs, have top of the line soft furnishings, and balconies that brings the outdoors inside and widen the vista.

http://www.casasurhotel.com