Hey 2F/2F -
Thanks for the tip on the Tamrac strap.
I've found nothing that surpasses plain, old suede leather (especially padded) for staying put on my shoulder. It not only has good "staying put" power but cushions nicely as well. I have an old, worn out camera bag with a suede strap and it's my favorite carry bag b/c of the way the suede holds on.