For many years now, I have had a user interface which is driven from the keyboard and is customisable (to a probably unreasonable level). This started with ratpoison, continued with fvwm and finally settled on xmonad. All of these were/are configured to do as little as possible to interfere with a terminal session (uxterm or urxvt) that runs "screen".
The use of graphical utilities is limited to situations where text-based alternatives were unavailable/impossible:
A conky/xmobar line which shows me some current info.
Accessing certain commercial websites needs Iceweasel/Firefox
Editing/Annotating PDF files and forms needs flpsed, xournal
Some people send me word/excel/ppt files which can only be edited using OpenOffice/LibreOffice
Viewing PDF files, DJVU files and pictures required Evince. (Though it has recently stoppped supporting PNG/JPEG files to my annoyance!). Occasional rare uses of video using vlc.
and (of course!) the time-sink called sgt-puzzles.
Network connections are handled through a number of scripts that handle wireless (using wpa_supplicant), ppp, openvpn, ssh, socks etc.
In fact, even other hardware related issues such as volume control, multiple displays (for presentations), suspend, etc. are all handled through such scripts and keyboard controls.
A colleague who works at MicroSoft Research looked at my laptop and declared me "masochistic", little realising that using the touchpad and dragging things around (especially text!) is what I really find painful/pointless. My personal computer (to paraphrase the advertisement of a big computer firm) is "truly personal again".
However, there is one major drawback of not being "mainstream". The configuration that one uses is not checked sufficiently. There are not enough "eyes" to "make all bugs shallow". When I had the time to be more active with Debian development, this was a good thing as it meant that I would find, report and (occasionally) fix bugs in the packages that I use.
So in the interests of laziness on the computer front, it would be nice to have a more "modern" GUI, which:
Is "mainstream" enough that common features for configuration and mobility would be ensured by in-built functions provided by upstream authors.
Is customisable through text-based editing if required. A reasonable programming language for customisation would be a "plus".
Will not interfere a full-screen "screen" session when instructed to stay out of the way!