At the YMCA my instructor likes this one for calfs & glutes:
standing beside the platform (step), put your left foot on the platform and your right foot on the floor behind it. Then get up on the toes of your left foot (like pointing your toes). We use barbell weights either holding in our hands or holding on the shoulders (for more effect).
Then raise up on your right toes, straight up, not "rocking" - as you come up, squeeze the glutes. However many reps, then change sides.
No need to have a platform, you can do this on the floor, too.