I would strongly disagree with the notion of "pushing kids out the door if they don't have the bug". If choir is an elective class, the fact that they're in your door in the first place is enough! It shows that they have an interest, and if you're trying to build a program, that should be your only criteria!
The only caveat to this that I'll mention would be if you have students that are only in choir because it's an easy A grade, and a class period they can treat like recess. If that's the case, (hopefully it isn't!) you would need to increase your own standard of classroom management so that the students are focused and on task for the full period. Once that happens, the students that are only there for "recess" will either decide they like singing or drop out of their own accord.
Recruiting is ALWAYS a challenge, but here are some key points to remember:
- If you have a strong and established program, students will recruit themselves.
- If you have a new program that is exciting and engaging, your current members will recruit their friends.
- Don't be afraid to give a little sales pitch at the end of a student assembly performance!
- See if you can get an invitation letter sent home with the entire student body before it's time to pick classes for the next semester.
- Some choirs find themselves "top-heavy", and have trouble recruiting male voices. Make sure you don't set yourself up for this problem by creating a stigma!
Repertoire is yet another challenge, and especially given that our current culture tends to glorify the fake and overproduced sounds of Glee. Lousy pop arrangements are a dime-a-dozen--DON'T program repertoire just for the title! If you do popular music at all, make sure the arrangement is sound and educationally beneficial. If you have students clamoring for the latest Glee hit, use the moment to teach them that Glee is not actually what the human voice sounds like, and the types of stage shows that they see on television are really only possible at the high school level with about three hours of rehearsal per day (see also Japanese public school extracurriculars).
I love the idea of programming music from the cultural heritage, but as you said, it may be a challenge to find suitable arrangements! You may even have to write your own arrangements, and possibly enlist the help of a local native music expert to actually find some of this material. It can be a daunting task, but not unheard of! Some band teachers struggling with instrumentation will even re-arrange everything they play, and this process is only made easier with accessible tools like Sibelius and Finale.
Outside of the pop/cultural heritage music veins that have more instantaneous appeal to your students, at the end of the day, as their director, YOU are the greatest advocate for the music you program! (I would in fact say that your job as a conductor is to be the advocate for the music you are performing.) Your attitude is everything, and you can make or break a piece for your ensemble based on how you approach it.
Classical music doesn't necessarily mean anything to your students if they don't have prior experience with it. They aren't going to understand the musical merits of Bach, Faure, Mozart, etc. until you teach them, and you can help to generate this appreciation by linking that material to non-musical things that they do understand. For example, storytelling about the origin of a piece of music, or what was happening historically that influenced its composition.
In this way, choir can be a kind Music Appreciation class with an emphasis on performance. Personally, I find many choir curricula to overemphasize rote learning when they should be learning General Music/music literacy skills and applying them directly to material for performance. You can further use this to your advantage by linking these new skills directly to the classical repertoire you program, thus enhancing both the skills and the enthusiasm for the material.