The colour scheme. White screens are one of the things that trigger my migraines.
This in turn leads to my modifying several other visual aspects of the desktop, because a lot of widget set themes come with scrollbars that don't work well with really dark colours. I also turn animations and automagic snapping and desktop navigation facilities off, because I find them annoying. Kindly behave like it's 1999 and don't do anything I don't explicitly tell you to do, Mr. Desktop.
And then I embed a conky instance in the second desktop for general monitoring—CPU activity (composite and by thread), memory in use, disk space, network usage, temperatures, fan levels, and greediest processes all conveniently in a single view that doesn't require me figuring out what I did with the window.