Two planes about to take off from National. I rather like Southwest Airlines' Canyon Blue livery (above) the best, although I do like the colors on Delta's Upward & Onward tail feathers (below).
"Delta's current livery is called 'Upward & Onward'. It features a white fuselage with the company's name in blue lettering, and a widget on the vertical stabilizer. Delta introduced its current livery in 2007 as part of a re-branding after it emerged from bankruptcy. The new livery consists of four colors, while the old one (called 'colors in motion') used eight. This meant the switch saved the airline money by removing one day from each aircraft's painting cycle. The airline took four years to repaint all of its aircraft into the current scheme, including aircraft inherited from Northwest Airlines." ~ Wikipedia