I wear Keen Commuter sandals exclusively. I sold or gave away all my other bike shoes, in a fit of minimalism.
I love my sandals! In the winter, I pair them with wool socks, but I only ride when it's 50F and above, so no problem there. In the summer, no socks.
Most of our rides are utilitarian, so it's great to have the sandals on for walking around in markets and such.
Emily
2011 Jamis Dakar XC "Toto" - Selle Italia Ldy Gel Flow
2007 Trek Pilot 5.0 WSD "Gloria" - Selle Italia Diva Gel Flow
2004 Bike Friday Petite Pocket Crusoe - Selle Italia Diva Gel Flow