According to Xfce FAQ the answer is no - the position and a size will be saved only when the application supports it. <
The one possibility for windows placement I'm aware of is similar to that used in Windows 7 <= OS - one can drag a window to the side or a corner of the screen in order to make it occupy a half or a quarter of it.
However if You use some programs on a regular manner, You can save Your session, so on each login, applications will be at the same positions, as during logout.