All of these flats come in black...for some reason when I copy the pictures over they all changed colors #bloggerfail. (and yes these are affiliate links but I have never earned any money from my blog - this is just an easier way for me to post the links)
Anyway, I think the Toms shoes (top left) are adorable and perfect for spring and summer. The CeCe (top right) is a classic ballet flat that has amazing reviews. These could work with something dressy or a casual outfit. I love the idea of a d'orsay flat and these Franco Sarto shoes (bottom left) would be a less expensive way to get in on that trend. The trendiest of the bunch though is the lace up flat. I love these from Anthropologie (bottom right). These might be less versatile but they are amazing.