One of the most interesting views of learning Spanish is that if you want to volunteer in a country where it is the native tongue, you have nearly 12 countries to choose from in 2 continents.
Remember that while the Spanish language will be similar across all of the latin countries, accents, slang, and words will change depending on where you are. Spanish Immersion programs change from a weeks to a few months, and it's important to select a project that will be customized to your schedule and language goals. You may not become fluent, it can help you overcome the basic language barrier. The longer you take lessons the more fluent you become and with the help of the local hots family you will be able to practice and improve many times your level of Spanish.