I have several terminals I leave in their own part of the screen.  I have focus follow the mouse , so to switch to one of these terminals I move the mouse. When I press alt-tab, it's never because I want to switch to or see these windows, it's because I want to bring up a hidden or partially obscured window. With focus-follows-mouse alt-tab should only affect windows that are stacked.
(Because in my case "non-overlapping windows" and "XTerms" are synonomous, I can set Compiz to do what I want by turning off alt-tab for XTerm windows. I like it a lot.)
 On my my desktop. On my laptop I run everything full-screen.
 When I move the mouse over a window and start typing, the text shows up in that window. The "focus" switches between windows based on mouse location. See