Regarding the flavoring of these cookies, I love the flavor of equal parts vanilla and lemon extract, which yields a cookie with more depth than just "sugar" while not tasting discernibly like vanilla or lemon. Feel free to use all vanilla, if it's what you've got.
As for the icing, I find that just a small amount of almond extract transforms Royal Icing into more of a true confection and less of a cloyingly sweet, one-dimensional glue. Again, the almond flavor isn't distinct at all.
Finally, the time noted in this recipe doesn't account for chilling the dough OR icing the cookies, which can vary greatly. If you're short on time or patience, the rolled sugar cookies, sans icing, are almost as tasty as their gussied up counterparts. :)