Rhonda N I've been practicing since 1999 and teaching since 2005. I think creativity can come from a lot of places. This series is different from others I've done, so it was harder to develop a class flow while having just one movement focus.
For group classes, I pick body parts or movements. I think it's important to have a basic structure. For reformer, mine is usually warm up/footwork, supine arms/legs, seated arms/legs, planks, box, extra exercises and stretches and then I just insert exercises into those slots. I also try to make sure that I do multiple exercises in one position before moving to another position.
I also think taking a lot of classes can help creativity. A lot of my workouts are calisthenics and strength training now, and they used to be barre and yoga, and I try to translate to Pilatesish.