Deat Takashi,
My piece of advise is:
- If you are going to take a taxi or remis, get it in the official stands that are just after passing customs. In the same area of customs you will find a Banco de la Nación Argentina to exchange money. Do not exchange money in other stands, the best rate will be the one of Banco Nación (national bank).
- If you want to get to the hotel in a more inexpensive way go to the stand of Manuel Tienda León bus to "Terminal Madero" http://www.tiendaleon.com.ar/home/home.asp It costs ARS 40, you can pay with credit card. Once in "Terminal Madero" take a taxi to the hotel. Every taxi driver should know where this hotel is and the price of the journey should be not less than ARS 13 and not more than ARS 20.
If in trouble show this text to the taxi Driver:
"Lléveme al Hotel Bauen, en Callao entre Sarmiento y Corrientes. He sido informado del recorrido y el precio que debo pagar por el viaje."
(Take me to the Bauen hotel, in Callao Street between Sarmiento and Corrientes. I have been informed about the price of the journey)
Carlos.