A left-hander, I always map keyboards to put Alt-Shift-Ctrl running up the left side of the board, and use the left Alt and Ctrl almost exclusively.
As a touch typist, I automatically use the Shift key opposite the hand that’s hitting a key (e.g., right shift for T, left shift for P). I figured that’s what everyone does, but apparently not.
For the Win key, it depends on the board. On the Omnikey I’m using at the moment, Windows is mapped to right Alt. (I really didn’t use the Win key until Win8 came along, but I use it a lot now, since I’m not a fan of hovering the cursor in corners in search of a charms bar.)