I'm a current college student and I know there are lots of companies in the USA who offer study abroad experiences in Spain. For example,
CIEE is one that some students from my university have used to go to Spain. If you go with a company from the USA, chances are the credits will be easy to transfer back to universities here. My friend just organized a study abroad through a company called CEA I believe? Anyway, I know they exist but they're somewhat more expensive. Of course, they take care of everything for you - you just send in the application and they organize everything.