I honestly have never seen anyone wear a curved band alone. If you wanted a band to wear alone, you'd either need to get a straight wedding band or an extra band if you decide on contour to wear with the e-ring.
Here's one that I have from an engagement that didn't work out. I'd really like to use it for when I really do get married. I would agree with others here that it does look a little strange on its own, but to each their own!