In Revit 2013 they removed the ghosted surface option, don’t freak out just yet, they also removed the transparent option as well.  This still isn’t the time to freak out.  The reason both of the features were removed is due to the fact that they merged to two together, if you think about it this makes total sense, because 100% ghosted is transparent after all.  They both have been replaced with Transparency and this is an adjustable slider.  I like this new feature because now I can make the walls more “Ghosted” or transparent then floors etc.  The combination can be set however you need or want it to be.  Minor change but a good one in my opinion.