Having poked around a bit, it seems like the Claridge -- despite it's 5 stars -- may not be a great place to stay these days. Apparently the "star system" is very unreliable in Argentina.

The Argenta Tower hotel (a 4 star) has been recommended to me. Anyone with any experiences there? The "negotiated price" seems to be about $75. I'd welcome any other hotel suggestions (doesn't seem necessary to spend over $100, though).