Summertime in Buenos Aires is a little oppressive. Usually January and February are the worst months to be in the city---most people take their summer vacations on January---so besides the heat and the high humidity nobody is there. That could be bad or good, it really depends on your mood. We've had some wonderful times when the city is half empty (for instance, restaurants and bars just for yourself is not a bad thing).
But if you are tired of the cement and want to rest in touch with Nature ---without going to Punta del Este---there is an alternative in the nearby town of Carmelo (Uruguay): the Four Seasons Resort. It takes a short plane ride and you are there, in the middle of a wonderful pine and eucalypt forest on the bank of the Rio de la Plata...surrounded by wonderful buildings in stone and wood that look like they belong in Bali.
The service is impeccable--- Uruguayans are extremely polite and relaxed--- and so is the Spa. There are tennis courts, a gym, a golf course, a wonderful club house...
This place is great even in winter time, because all the rooms and bungalows feature wood burning fireplaces... great for that romantic getaway.
Welcome to Paradise.