I love Patagonia's Maha Breathe (in black). It's stylish, comfortable, and city appropriate:
http://www.patagonia.com/us/product/...?p=79684-0-155

Although they are described as very casual, they're really sleek enough for everyday city wear (they won't work with formal business attire, but they are professional enough for most circumstances). I live in New York, and wear these everywhere and with everything (skirts, dresses, pants, whatever). I routinely (3x or more per week) walk from the mid-50s to 14th street wearing these shoes. I wear them all day. All night. I love these shoes.

Basically, they are like ballet flats, but are much more comfortable, and the mesh part makes them great in warmer weather (but I've been wearing them all spring, even in 50 degree weather and have been happy, or with tights). They dry quickly if you get caught in the rain, and mine still look new, even with all the wear.