^^I'm too lazy to dig out my bags to take pics, but you can use these pics as a gauge - the same laptop is featured against all three bags, so you can get a feel of the sizes.
Courier vs Work vs 13.3 inch MacBook Air
Velo vs 13.3 inch MacBook Air
Day vs 13.3 inch MacBook Air
Great pictures!
Do you think your MBA would fit in your Velo if it were in a protective sleeve?