CASA DE LA ALEGRIA(house of happiness). I think this place is on Pasteur, about 100 block, close to the main plaza. I passed by it often on my way to the central plazas, but I can't find a hotel or restaurant under this time in this location.
La CASA AZULat Allende Sur 6. It is located on old San Agustin Street only a few steps from the San Agustin church & the ex convent which currently houses the Museum of Art, both outstanding examples of Baroque style in the world.
Their web site with many room photos:
GRAN HOTEL at Juarez Sur 5This 5 star hotel, which opened in 2006, is located on what was once part of the adjacent San Francisco Convent in colonial times.
Their web site includes a virtual tour:
GRAN MISSIONES (Madero 15)The current building incorporates major alterations from the 18th& 19th centuries. Nothing remains of the original 16th century construction.
Their web site: