I have the same issue, about 2/3 of both feet are numb. I was having issues feeling when my feet were on the pedals and having them pop off ofter a bump. Also slipping off when I had either just the edge of my toes or heel on the pedal and pushing, makes for an interesting ride.
I had real trouble finding shoes big enough that were wide enough, I usually take a EE or EEE. I finally found a WIDE in a size 13 (I wear size 12) that was wide enough on Nashbar.com, took a risk that they would fit and ordered them. They were the store brand no-name so they were nothing special and probably they don't sell them any more. I got the genuine SPD pedals Shimano M424 Mountain Pedals which have double sided SPDs and cages on them. I find pedals without cages hard to start on from a stop so they work ideally for me. The pedals / shoes definatly help with the issue, I feel more secure knowing where my feet are and the extra ommf of the clips helps in the hills.