HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\ComDlg32

To disable the Places bar, create a REG_DWORD value named NoPlacesBar under the ComDlg32 key. Leaving this value as 0 will give you the default behaviour, while setting it to 1 will remove the Places bar from the common dialogs.

p.s. nuhi that's for you, this should be in nLite along with NoFileMRU and NoBackButton.