Kona
I tend to favor the Logitech MX518 mouse - the one that looks bullet riddled. Primarily because it's light and that puts less strain on my hand moving it around but it still feels good button/wheel wise. Wireless mice are right the hell out as the batteries make them instant torture devices.
I don't use pads or gel strips or whatever. Those don't tend to work for me at all. What I found last week, actually, is this hand glove thing:
http://www.amazon.com/Imak-Computer-Glove-EACH/dp/B000FEVWU8/ref=sr_1_15?ie=UTF8&qid=1333101559&sr=8-15
And THIS actually seems to work for me. I can rest my wrist on the padded part and it feels pretty good. Doesn't help my shoulder but I'll take what I can get. :)
As I said before, I also get a deep tissue/trigger point massage once a month as a maintenance thing. She works out all the knots in my back/shoulders/neck and tries to reset me for another month.
Sorry to hear about your troubles. Mine doesn't sound as bad as yours but that might be because I've found a maintenance routine that helps keep it under control somewhat.
Good luck!