You have to apply for the Schengen visa at either the consulate of the country you plan to stay the longest at, or if staying at all countries equally, at the port of entry.
For the Italian consulate in San Francisco, there is an option to mail your 'verified' documents instead of appearing for the interview.
YOU MUST APPEAR IN PERSON to apply for a VISA or you may submit your application to the Honorary Consul for a prescreening and then mail it to the Consulate General.
Italian consular website
If you have any further questions, you could email them. They respond within a day usually in my experience.
I could not find any similar option in the Greece consulate in San Francisco.
Greek Consular website