Speaking of Gnome, just for kicks I was planning to build Garnome when I had the time, though there are some dependencies that we don't have yet. It installs into it's own directory, can even install in into home if I remember. Being self contained would make maintenance much easier, as maintaining a modular Gnome would be very time consuming.
EDIT: Though Garnome installs self contained, it is a full Gnome install with full functionality and no option to install a basic minimal setup. Most likely I won't go that route.