After baking my "Goldilocks" version of the Sprinklebakes/Williams-Sonoma cookie recipes, I was reasonably happy with the cookies. They were softer, but still flat enough to be aesthetically pleasing; a happy medium. However, the very next day I tried a recipe given to me by one of my sister's friends; it has been in her family for years now, and my sister loves it. It was fantastic! Flat, light, chewy, delicious. I found a winner.
Now, for the icing. I creamed together a batch of the same friend's buttercream frosting; it tasted heavenly, but was still not entirely dry five days later. I do not think it would withstand being stacked and otherwise packaged, especially not if each cookie was fully flooded with icing. So, since my sister liked the royal icing, I will stick with that. It dries shiny and hard, looks beautiful, and tastes good to boot. Furthermore, it is naturally white due to the absence of butter -- the butter in the buttercream turned it a soft yellow -- so should be a better backdrop for food coloring.
I will, however, plan to use the buttercream frosting for my sister's bridal shower cupcakes!
My remaining task is to figure out the best way to ice the cookies and somehow write my sister's and her fiancee's names on them. My "Message in a Cookie Cutter" cutters are wonderful, but once I ice the cookie, the lettering disappears (covered by the icing). So I believe I have two options: (1) use the stamp over the icing when it is nearly dry, so the stamp goes directly into the icing; or (2) write their names on the cookie in a color different from the background. E.g. I believe the wedding colors are yellow and navy blue, so I could do a yellow background and navy blue lettering, and/or vice versa. Maybe each guest could have one of each. The tricky part with this option is that it will likely be much more time-consuming, and I will have to bake and ice plenty of extra cookies in case I mess up the lettering! A small price to pay for perfection....