Hi. In January 2004 the Marriott was very comfortable. In a good neighborhood -- due to changes in BA actually a better neighborhood for tourists now than Alvear Palace. Not a typical Marriott, it is a lovely Beaux Arts building. The rate was in USD, under $150/night for a view of Pl. San Martin and breakfast. Maybe it would be less using one of the online sites, but I thought it was a good value.
