So, having "graduated" from physical therapy, I've now got the job of managing my shoulder recovery on my own. I've learned two things recently:
1) Some days I wake up with a very stiff and sore arm. (The locus of the most pain has actually shifted from my shoulder to just above my elbow where the biceps tendon inserts. My physical therapist told me that this is normal.) Doing 30 to 40 minutes of upper body exercises (lat pulldowns, push ups, bicep curls, triceps extensions, and horizontal rows) does wonders for loosening everything up and reducing the pain. The trick is getting through the first 10 minutes without either sitting down on the weight room floor and crying, or going and doing some leg exercises that don't *hurt*.
2) I can do YTWL's again! YTWL's are one of the best exercises I know for strengthening the rotator cuff muscles. I've tried doing them at various points during my recovery from this injury, and have always found either that the movements were too excruciatingly painful or that my range of motion was too limited to make the exercise seem worth doing. I tried a couple of sets this morning after the aforementioned 40 minutes of upper body exercises, and it was manageable.
Progress sometimes seems frustratingly slow, but there is progress.