my whole workflow is based on the quaintly named "classic desktop model" where screens and windows don't magically resize and change position (...) I'd switch to LXDE or XFCE, but they're a little too light-weight for my taste
What does "a little too light-weight" mean? Something like JWM or icewm?**
LXDE has a useful set of features and it won't waste your time with unwanted "special effects". If you really are frustrated by the barkers at the KDE-Gnome-Mate-Cinnamon desktop carnival, I suggest that you try Debian LXDE or even Lubuntu.
The configurable simplicity of LXDE is the main reason to use it. (http://en.wikipedia.org/wiki/Comparison_of_X_window_managers)
One of the main reasons why the Debian folks switched from Gnome to XFCE was that they couldn't fit Gnome on a CD anymore. The fact that the market is abandoning optical disks in favour of USB/SDHC booting doesn't mean that I want KDE/Gnome bloat.
**Disclaimer: I use icewm on my Raspberry Pi(s). The icewm DE light, simple, and easy to understand. Oh yeah, and the R.Pi won't run much else very well anyway. (o;