There are many good reasons for English to be the official language, it would save money, make the states more united, and allow for better communication with immigrants.
English is spoke by 80% of all Americans 5 years or older in their homes. English is used in the majority of all court room settings, and in any bills or laws presented before congress or the presidents office.
The country as a whole would cut cost on paper and printing by keeping the forms to one simple language.
English is also the offical language of 51 other countries, and is a language that other countries teach so that their children can prosper here in America.
There is no draw backs from making it our offical language, and could honestly be a good stepping stone to heal the country in bi-partisan support.