I actually was in a wedding in November where the bride attach I Do to the bottoms of the shoes, in the arch area so it didn't get dirty and fall off. Although it was underneath the shoe, it was still cute.
I almost wore those exact same shoes! I fell in love with the heart on the bottom. But unfortunately I'm 5'9' and my husband is only half an inch taller than me, and I preferred not towering over him on our wedding day! :)