I've found that for rainy day riding, my Crocs with wool socks work quite well for rides of less than 20 miles. They don't hold any water, but still give your toes a bit of protection, which my Shimano SPD sandels did not. Even if they are wet, wool socks will still keep your feet warm. They aren't particularly stiff, but more and more the biomechanics of many cycling traditions are being questioned by scientific studies: stiff may not be more efficient, clips or clipless may not increase your power on the upstroke, ankling is highly doubtful, and they are even telling us that cyclists don't sit on their sit-bones. Try lots of things, starting with what you already have, then use what seems comfortable for you.