I personally like the aesthetics in KDE 4.x as seen in Kubuntu and Sabayon 4.0 (http://www.sabayonlinux.org/screenshots). I prefer dark themes (easier on my eyes) and they just look slick.
KDE has the advantage over Gnome in aesthetics whether light or dark themes are used. Gnome with Metacity just tends to look kind of flat and boring. And, the default Ubuntu themes are especially boring and funky looking to me, the orange and brown in windows just doesn't do anything for me (although I really like the wall papers in Hardy and Intrepid, very artistic and cool looking).
I'd like to see more wow factor in the default theme for Ubuntu, so you can show it off to your friends on their computer with the live CD. Also, a better default dark theme would be great. DarkRoom is not at all attractive.