It is against Delta policy to sell the Gold so you could give it to somebody who will be as altruistic as you are and give you something too (please note I did not write "back").

Personally I dont think giving Gold to my Wife makes sense. Here is why; when we fly together on one reservation, I am pushed down to Gold. So the single gal/guy with Gold status actually gets it faster to the front of the plane that two of us together.

On all long distance flights (transcontinental) it is difficult those days to be upgraded to first if you area Diamond (on top of D status I have Amex Delta Reserve). So when we do fly together she gets my seat in first, and I go to seat in the back and for re-education. Plus I am scoring extra points with my Wife for being (still) so charming.

Those SWU were/are great if you flying on AirFrance or KLM and willing to chip in more money and get an upgrade. I did fly once in so called economy comfort and once in Business on KLM. Both flights IAD to CPT via AMS.
I must admit that I don't want ever to fly in the back. Not even as some researchers claim my chances to get killed in front of the plane are much bigger. I would rather die in class.

Also I do see Diamond tags being sold on ebay for 125.00 a pop. You can buy bigger/shiner Tiffany for 250.00 extra, and if you really give a #@$% make a color copy of them before you sell, glue them over your good, old Platinum tags. Trust me nobody will know the difference. Unless you let them touch...but this would be either consensual or harassment.