I know I can get an IDP, but I read in some places that they recognize US Driver's Licenses specifically New York. Can anyone confirm?
According to this USA Today article you can't.
Afaik, an international license is mostly a multi-lingual translation of your national drivers license. In theory, you might avoid needing one in nations where police commonly speak English, like Scandinavia, Germany, etc., although officers might still demand one, depending upon how national laws are worded, the officer's dislike of foreigners, etc. Spain cannot expect that its police speak English, so yes you'll need the international one. You'll probably still need it even if the officer speaks English because their laws would be written assuming the officer might not speak English.