The 'radio switch with icons' looks good to me. One would only need to design two icons, one to represent the 'places' arrangement and the other to represent the 'directory tree' arrangement. Then as it seems to be slim (low hight) maybe it could even fit in the status bar, in the far left.

If using a traditional toggle button (like the first image) then it could go in the toolbar. Although now and then it seems that some people complain of it having 'too much buttons' (I don't feel like that although the current 'home' button is redundant with the side panel shortcut).