Built-in Control Panel:

A new option instead of the power pack tray is a built-in control panel.  The  frame can be expanded by 8-10" on one end or the front of a layout, to accommodate a recessed wood platform.  Plenty of room is available for 2-5 power packs and controls for turnouts, lighting, or turntable.  See the Ammergau photo below left, and the Traunstein, below right.