Janet2K, per your request, here is a quick summary of my family's experience with the silver plan add-on to our Fairy Tale Package earlier this month.
My daughter and I stayed at the Boardwalk Villas (one bedroom) with the Fairy Tale Package in early August. Sometime after making the reservation, I added the silver plan (two wisher per person per night and a couple of other features--preferred viewing for fireworks at the various parks, etc) because I had planned on a few visits to the (Disney Institute) DI (now Saratoga Springs) Spa as well as meals at the more expensive sit-down restaurants. Edited to add: we did not use the special fireworks viewing and the other item--I believe it was some story-telling session.
Well before our vacation began, the DI spa was closed.
Upon check-in at BWV, the CM reviewed components of the plan as well as use of the wishes (they are good until midnight on the day of departure) and explained the wishes had been programmed to our room key card. We were also given a brochure about the wishes (merchandise, restaurants, services, for which they could be used).
Now that DI spa was closed, I had to do some refiguring. Since the DI spa offered vastly different services (IMO, much better services than those at the Grand Floridian spa), I called the GF spa to find out if they would provide the same or similar spa services as the DI for the same amount of wishes. The answer was no (GF spa services were limited to Lavender bath, head and neck massage, and sinus relief therapy--you can see why I was not thrilled with these options
), but two wishes could be used for a massage. Note, this is currently not listed in the brochure.
My views on the silver add-on:
Definitely convenient. For each purhase, your receipt lists the number of remaining wishes so that you can plan accordingly.
Should be considered by those who factor in regular sit-down meals as part of their WDW vacation experience
Should be considered by those who use the various recreational activities/services offered by WDW (e.g., child care clubs, golfing, boat rental, etc).
In summary, I enjoyed the convenience of using this plan and felt I received good value for the amount of money I spent on the plan. Note, for the higher-end restaurants at which I dined, I had planned on dining at most of those restaurants anyway, so getting the plan primarily for meals was not the major consideration. Despite the meals and use of the plan for childcare and spa services, it took some planning to use the remaining 3 wishes. Using wishes for merchandise (other than pins--my daughter is into pin trading) was not a consideration for us because the merchandise items were of absolutely no interest to me and I am just not into tchotkes--e.g., lincoln log set of the Wilderness Lodge, some type of desk box with Mickey Mouse or some other Disney character; these things are not my cup of tea.
Would I purchase this plan again? Only if I planned on purchasing spa or other entertainment/recreation services--and the services/items offered were of interest. IMO, it would be nice if WDW would consider a change in its policy and allow for wishes to be used for children's programs/activities at the resorts (e.g., any of the Grand Adventure activities at the Grand Floridian). Now that my daughter is 10, she will be over the age listed for the GF children's activities. But if WDW ever offered GF-type of program for 'tweens' at the GF or one of the other resorts, it would be nice if wishes could be used for those types of activities.
From a meal perspective, the wishes are useful, but I would prefer a separate meal voucher program, and definitely one that offers more flexibility (ability to purchase vouchers/wishes, whatever, for those in your party who will actually use them--wishes are not a good value when used for children's meal), ability to order, for example, two appetizers and a salad instead of soup/salad/appetizer, entree, dessert; depending on the restaurant inclusion of wine.
If there are questions, I'll be happy to try to answer them.
Thank you for your wonderful posts. This was just what I needed to help me plan the use of my wishes. 
