This model (http://www.mec.ca/AST/ShopMEC/Cyclin...g-panniers.jsp -- $59 for a pair) has hooks for a shoulder strap and a few more pockets to organize things.
A shoulder strap costs $4 http://www.mec.ca/AST/ShopMEC/Packs/...lder-strap.jsp.
I have an axiom rear rack and it's fine.