A nice theme for the desktop is not super important. OK, it has to look decent, but on my main computer I hardly see the desktop theming, or the icons. I just see the application I use. When the main application is Emacs, and the second a web browser, themes of the desktop does not matter much. However I found this, and I must say it looks really good. I checked the config files, and saw that the owner of the destop has developed the theme used. So I downloaded it on one of my old computer, which has xfce4 as desktop environment.