airport transit visa or regular visa?

[emiliobrr]

Dear Sir/ Madam,

I am not an American citizen. I am traveling from the U.S to Berlin, Germany. However, I have a layover in Milan, Italy. I am planning on going to Berlin, Paris and Barcelona over a period of 3 weeks. I am leaving from Paris to return home to the U.S. I am not staying in Italy, but I am not leaving from the same airport I came in? Which visa should I apply for, the airport transit visa or the regular visa?

Thanks in advance