I won’t throw stones in the Gnome/KDE debate. KDE is obviously on a more robust development track, but I’ve always preferred the GTK approach for its speed and clean layout. It’s a drag that Patrick is no longer supporting it in Slackware, but Dropline is an excellent way to manage it.
Of course, the one thing Gnome lacks is the ability to change color-scheme on the fly. KDE, WindowMaker and even Blackbox have utilities for this, but not Gnome. You have to rely on individual static themes for that, and let’s face it, most of them are garish and poorly designed for everyday use.
One of the interesting forks of the GTK toolkit has been Xfce. Olivier Fourdan’s default theme has a nice, clean interface that strongly resembles the “Plastic” KDE theme (it works under Gnome. You can get the engine here.). The config file is well-written and easily hackable, and it’s what I use 98% of the time, so I’ve taken to writing variations to it. Continued...