get Scentific Stretching by Tom Kurz for the best thing I have read on stretching.
For the upper back and shoulders, a good stretch is to grab a broom handle overhead as if you have just snatched it. Now stretch your hands back and down and pull your hands apart.
Return to the start position, move your hands out an inch on the broom handle and repeat.
There is another stretch where you hold the broom handle in front of you with an alternated grip now circle the broom handle with the palm up hand going over the palm down hand until you have turned the broom handle 180 degrees, tighten everything, return to the start position, move your hands in an inch and repeat. (harder to explain this one without pictures)