I have middle and high school students whose English actually seems very reasonable. I was thinking about asking them about things they want to learn and things they think are important, since they already seem very keen students. Unless, do you think it would be a bad idea to do so?
I tried this with students back home and it was helpful because I used it to choose comprehension passages about topics they were already interested in. For ESL, I usually ask my students what their ultimate goal is in learning the language - they'll probably tell you they want to speak fluently. I ask specific questions like: Do you want to be able to read English novels? Do you want to watch English moveis without subtitles? Do you want to study at a foreign university? It gives me an idea as to what type of language they would prefer me to focus on.
As far as content is conerned, teenagers here aren't much different to teenagers back home. Some middle school kids respond very well to k-pop, others could care less. They're pretty curious about what life is like for teenagers in other countries. I've taught a couple of middle school kids here and they've often commented on English tv programs (Glee is pretty popular), social lives of teenagers, differences in dating, differences in education approaches - stuff like that. My high school kids are also pretty keen on some of these things but it definitely varies from school to school (based on economic status, location, proficiency, etc.). To give you an idea, my kids were fascinated to hear about Amish people and it led to interesting conversations about modern technology. We've done lessons on dating etiquette, superheroes, tv programs, extreme sports, movies, computer games, comics, etc.
Ask your kids what they're interested in - it doesn't hurt to find out what they like and do some research when planning lessons. What I wouldn't do, however, is become too focused on matching every lesson's theme to what your kids have said - sometimes they need to cover material they are not 'interested' in because otherwise they'd never be exposed to anything other than what they already know; plus, you would want to shoot yourself if you didn't have the same interests.