I've been using clipless for maybe two months now. I can't really give you much advice, except to say that I've got two pairs of bike shoes. One is a "mountain" shoe, with a very stiff sole, snug fit, and a lot of power, but great difficulty to walk in. The other is a "Keen commuter" sandal, which isn't quite as powerful because it's looser, but you can walk around in them and forget you're wearing bike shoes. I got them to be able to bike to the beach and go swimming - the one I'm thinking of has a pretty rocky lake bottom and I don't like going barefoot.

Maybe the SPD pedals you have and a different pair of shoes is the way to go?