I share pvdecastro's view. I don't know if the Marriott has undergone an extensive overhaul in recent years, but I found it in bad shape about 5 years ago. I also found the service quite poor. It was a great luxury hotel ~100 years ago (the "Plaza"). I think the Alvear Palace may retain that charm, but the Marriott doesn't -- unless something's changed recently.

As had been mentioned previously on FT, the Hilton Puerto Madero also has the distinction of featuring prominently in the film "Nueve Reinas".