Shoulder rolls sound like a smart add-on. Do you roll them forward, backward, or both? I've tried it but sometimes feel it more in my neck, not my upper back. Trying to figure out the right form to hit those tight spots between the shoulder blades.
Roll them BOTH ways, but focus on squeezing your shoulder blades together. Keep your chin tucked slightly to stop your neck from taking over. Imagine drawing big circles with your elbows, not just shrugging. That shift in focus REALLY gets into those upper back knots.