Woah! 60 students in a class. That's big! I don't know if I could do that.
Even with small classes, I usually like to break up students into groups based on their level so that I can give a little bit more individual attention.
And Don, I agree with you about simple accompaniments. I think if you can't pull off an arrangement smoothly, you need to either work on it until you can do it smoothly (including singing the song at the same time!), or simplify the arrangement. I'm a big believer in keeping it simple. As a performer, I feel like I want people to be focusing on the songs and the singing. The guitar playing should support that. As I've gotten better and better, I'm able to carry off more and more complex accompaniments, but my main concern is for what is going to serve the song.
So, bringing it back to teaching, I often find with students who have more experience that I have to back them up a little bit and simplify their arrangements. I work at getting them solid on a very simple accompaniment before we go on to more complex things. Again, for me it's about being able to put the song across.