This is an international school in San Carlos, Mexico (near Guaymas--about 8 hour drive from Phoenix). They offer summer camps that incorporate immersion strategies for speaking Spanish.

 Here's the website:

http://www.colamex.org/summercamp/kids.php

They offer a Spanish, French and German summer camp--immersion style. There are 3 sessions that run for 3 weeks a piece. Here's the website.

http://www.isaz.org/summer_program.php

This is a Spanish Language School in Baja-- I don't know much about this one but the website looks great and they accommodate entire families that would like to stay together for an immersion experience. Here is the website:

http://www.bajacal.com/spanish-immersion-programs/family-program.html

This company takes high school students to Nicaragua-- NicaVenturaHS offers an all-inclusive international learning experience providing eco-adventure and historical tours, an authentic Spanish language and cultural immersion program, volunteer opportunities and training in the area of multicultural awareness. While schools attempt to prepare students for a "global economy" on a local campus, students who Travel To Learn get firsthand experience through structured and exciting activities while giving students a sense of accomplishment and positive self-worth. Students learn about history, geography and culture, social and economic justice issues, environmental issues and experience the power of helping others through service. Created by experienced teachers, the program fosters a learning environment at all times.

Here is the website:

http://www.itraveltolearn.com/nicaventuraHS.html

This is an immersion experienced offered to children and even families. You would need to travel to MN to participate. These villages have been functioning for quite some time and are top notch.