I actually took two in a series of Intermediate Spanish courses in back to back quarters, but I'm going to throw it out there that I don't remember the difference between the two. It seems that they were taught in the same classroom. I have no recollection of who taught the classes, but I do remember that some advanced Spanish students would come in to talk to us so we could practice speaking.
After learning a bit in junior high and high school and dropping my ridiculous AP Spanish class, over two years would go by before I would take another Spanish class. I picked it right back up again, though, and would actually do really well in both classes. These were probably the most important Spanish classes I would take, as they were beyond the basic level of high school Spanish and really prepared me by helping me solidify my grasp of the language.
I would talk sometimes with a girl in my apartment building who spoke Italian, and it was amazing how well we could understand each other. She wasn't Italian, just an American who spoke Italian, so with us both talking to each other in Romance languages and our American accents, it wasn't too hard to figure out what we were saying.
I still wonder what it is that makes so many Americans almost proud of the fact that they can only speak English. Learning another language helps you know your first language better by understanding how the various parts of speech work together. Having to consciously think about how all the parts work together helps you know why you're saying what you're saying instead of just saying what you hear, or think you hear, others say (like 'could of' where it should be 'could have' but who could of known which is right, since they sound the same when you talk fast?).
If you learn a language with a lot of the same Latin and/or Germanic roots as English, it can help you know what some of the more obscure English words mean, because they're similar to a common word in another language (like edifice and edificio, meaning building).