For communicative purposes, rhetoric is an amazing field of study. Many of the texts I used in college were crap, but Jay Heinrich's "Thank You For Arguing" is pretty phenomenal as far as being a quick and accessible primer to rhetorically-charged language.
I'd also suggest a good creative writing course (I'd pick prose over poetry, but they're your classes now); the workshopping process did a lot for me as far as developing a critical eye toward language. One could only hope that it would do the same for you.
Frankly, either will do you some good. The key thing to take away from this is not the course matter itself, but the implicit, generalizable lessons from it.
In both, you learn how to put words in their best order. It is just that each genre has its own conventions (multiple sets of conventions, in fact) regarding what "best order" actually is.
I'd also suggest a good creative writing course (I'd pick prose over poetry, but they're your classes now); the workshopping process did a lot for me as far as developing a critical eye toward language. One could only hope that it would do the same for you.