I used to use a tiling wm but now that everything supports dragging windows into a side of the screen to make them take up half the screen, I find that my main

I used to use a tiling wm but now that everything supports dragging windows into a side of the screen to make them take up half the screen, I find that my main usecase of tiling wm's: side-by-side windows, is handled well enough that I don't want to put up with the occasional annoyances. The main pain point of stock ubuntu gnome for me right now is that when I open too many windows, my alt-tab becomes too cluttered, and it would be cool if there was a way to designate windows as background somehow (but not different workspace, I don't like workspaces), so that it would not show up in alt-tab. Ideally I would be able to have like 40 open windows of which just a handful are "active". EDIT: The side bar could be used for bringing up windows if it didn't combine windows from the same program into one icon - a feature I absolutely loathe - seriously, I have a lot of empty screen real estate but instead you want to hide my windows behind a second click?