I gave up on KDE. It's ugly and I wasn't even able to make it all the way through my configuration process.
Now I'm in Cinnamon. It's still ugly, but a bit less. Ran through my configuration sequence without trouble. Scroll wheel acceleration rate feels weird and I can't tell if I'm imagining it; "disable touchpad while typing" seems to work worse than GNOME/KDE. This definitely looks, and feels, like A Linux Distribution and I don't mean that as a compliment, but really, I could maybe use this