The Best Place to Study Spanish is
The winner is Guanajuato
Guanajuato state's capital, this colonial city is vibrant and unusual. One of its principal thoroughfares runs underneath the city, which sprawls up the sides of a deep canyon. Tall, colorful, narrow houses overlooking narrow, twisty streets characterize the Old City. A university town, Guanajuato has a youthful population and many worthwhile museums.
A lively university town with great Spanish schools1
And the runners up are....
San Miguel de Allende, Guanajuato
Several major Spanish schools
Several different language schools in town
several major Spanish schools
Mexico City, Federal District (DF)
Study at the Uni of Michoacan or private CCL plus a few others
No schools, but lots of people who teach Spanish everywhere.
San Cristobal de las Casas, Chiapas
A popular place to study Spanish in a lovely, small town setting