Hi,
I lived on the old RAF Wildenrath married quarters from 2008 - 2012. It has now been closed down and finally handed back to the German authorities.
Both my Mother and father were stationed there during the 60's and this is where they met.
There are plenty of areas to metal detect around the old RAF station, but I would think the most interesting areas would be at the ends of the runway (certainly at the Dutch end) and in the woods on the far side from the hangers...This is where the ammo bunkers and gun test ranges were.
I suppose that any area within the old station perimeter will provide some finds.
Of interest would be the old WW2 German defenses to the West of the the staion. If you head South from the new roundabout (where the main entrance used to be) then take the 1st right, you will see a wood line on your right hand side..park anywhere along that road and walk into the woods and you will find old trenches and bunkers...the line is part of the Western Wall (Siegfried Line).