Make Plasma Semi-Tiling
Tiles are nice.

What is this? Windows set to a position and size. They will stay this way, in the proper desktop/screen. They are not fixed to some tile layout, they are still floating and can be maximized or moved around. They are just told to be there when they are opened.
How? Set the layout the way you want it. Then use the alt+f3 menu and choose More Actions -> Configure Special Application Settings. This opens a window that allows you to configure many rules for that application, including size, position, desktop, screen, decorations, and more stuff. You can set each to Force (always apply this and only this) or Remember (let me change it and just remember how I left it).
Why do you like this? Because I find floating windows more natural. But I also like creating layouts on different desktops. This way I’m not forced to open everything in a tiled layout, and just apply it to what I need. Flexibility to move or maximize stuff is kept. No awkward automatic tiling when I open something. Windows are just glued in place. And it works: When you login again you will keep the layout (though some applications might need to be started first).
BTW I recommend using alt+LeftClickDrag and alt+RightClickDrag to move and resize windows.
