See this recent thread on footwear:
viewtopic.php?f=71&t=24906&start=0Doesn't address width, per se, but has several helpful suggestions.
I have tried several myself (Keen's and Chaco's are great) but now use the Vibram Five-Fingers because they are as close as possible to being barefoot while still providing protection and traction on land. For me, the sandle styles have two disdvantages: thick sole (I'm 6' 5", need every inch of leg extension possible) and they allow debris to get caught under your foot.