I made a cake for an auction that is vanilla bean cake with chocolate buttercream, covered in chocolate ganache & then fondant.  The cake was baked Thurs night, decorated Fri & delivered on Sat.  The lady who won it contacted me today (Sun) saying she would like to save it for next weekend.  I've never stored a cake for that long, always make them fresh for events, so I'm really not sure what to suggest to her.  

What would you all suggest?

She will get the best result by freezing it. Refrigeration makes a cake go stale faster.

Place cake in cardboard box. Wrap box in saran wrap and a layer of foil.  Place in freezer until 24 hrs. b/4 serving.  24 hrs. b/4 serving, place wrapped box in refrigerator.  3-4 hours b/4 serving, place wrapped box on counter to come to room temp. Right before serving, remove cake from box.   Condensation will go to the cardboard and not the cake and it will look, and taste, like it was just made.

Yes, I've done it and yes, it works perfectly.

Thank you for your feedback :-)  I will give that a try.