I spent a few hours today coming up with choreography for my barbell class at work. I use the same CD and choreography for a month of classes and then I change it again, so I only have to plan like this once a month.
I purchase Powerflex CDs made just for this type of workout with separate songs for the warmup, squats, chest, back, biceps, triceps, shoulders, lunges, abs, and cool down and with spaces in between the songs so you have time to change your weights. I keep copies of my old CDs and choreography in a file folder. Once I plan a half a dozen of these classes, I'll probably rotate through my old music and choreography again. That way, I won't be repeating any music and choreography for at least six months and I'll be able to benefit again from all the work I am putting into planning these classes.
I definitely love my part time job as a group fitness instructor. I really enjoy coming up with my own choreography. Creating workouts and teaching them are gifts that the Lord is letting me use again. And lifting barbells to rocking music is my all-time favorite way to workout.