The CTX series has wonderful short cardio workouts. You could even put two together for one nice, long, intense cardio session. When I was saying interval cardio I was thinking along the lines of Imax, Imax 2, or Imax 3. You could also walk or run for cardio or do cardio workouts by other instructors if you have that option. When I think of circuit workouts I think more along the lines of BootCamp, Circuit Max, the High Step workouts, etc...cardio and weight circuits. If you want more suggessions you may want to post your rotation question on the open board or rotations board then more people would look at your question and you may have several ideas to choose from. Glad I could help a little bit!
Angela:7