The primary desktop environment (because it's the one I use myself most of the time) is Xfce, but I've had Enlightenment available as well. Recently, I've added MATE as an additional option.
OK, here's the obligatory screenshot:
While it's not quite as retro as some of the other desktop options, MATE has a similar philosophy to Tribblix - maintaining a traditional environment in a modern context. As a continuation of GNOME 2, I find it to have a familiar look and feel, but I also find it to be much less demanding both at build and run time. In addition, it's quite happy with older hardware or with VNC.
Building MATE on Tribblix was very simple. The dependencies it has are fairly straightforward - there aren't that many, and most of them you would tend to have anyway as part of a modern system.
To give a few hints, I needed to add dconf, a modern intltool, itstool, iso-codes, libcanberra, zenity, and libxklavier. Having downloaded the source tarballs, I built packages in this order (this isn't necessarily the strict dependency order, it was simply the most convenient):
- eom (the image viewer)
- caja (the file manager)
- atril (the document viewer, disable libsecret)
- engramap (the archive manager)
- pluma (the text editor)
- mateweather (is pretty massive)
- marco (the window manager)
- mate-themes (from 1.8)
The other thing I added was the murrine gtk2 theme engine. I had been getting odd warnings from applications for a while mentioning murrine, but MATE was competent enough to give me a meaningful warning.
I've been pretty impressed with MATE, it's a worthy addition to the available desktop environments, with a good philosophy and a clean implementation.